Saturday, 29 March 2008


Still dotting the London landscape, the ornate ironwork of these essentially utilitarian structures say a lot about Victorian design ethic.

© Christopher Seddon 2008

Thursday, 27 March 2008

Before Lucy: Earliest human ancestors

The term “Primate” is due to the 18th Century Swedish biologist Carl Linnaeus, representing his view that this group, which of course includes humanity, sat firmly at the top of creation’s tree.

To most people, the term “primate” means the anthropoids, i.e. apes and monkeys – creatures that bear more than a passing resemblance to ourselves. Nor do the similarities end there. Although we tend to think of ourselves as something apart from the rest of nature, characteristic human features such as intelligence, upright walking and our complex society all stem from our primate roots.

What is a Primate?
Curiously there is no universal agreement as to what unique traits can be regarded as defining features of the Primates.

Primates are one of 21 orders of placental mammal (Infraclass Eutheria). There are around 200 living species of primate, conventionally grouped as lorises, lemurs, tarsiers, New World monkeys, Old World monkeys, lesser apes, great apes and humans. They are typically arboreal (tree-dwelling) inhabitants of tropical and subtropical ecosystem.

Primate skeletal anatomy contains features characteristic of mammals in general but also some that are more specific to the primates. Like other mammals, primates have four types of teeth – incisors, canines, premolars and molars. Early mammals had three incisors (I), one canine (C), four premolars (P) and three molars (M) on each side of each of their jaws (or quadrant) – a “dental formula” of 3-1-4-3; but primates have lost the first two premolars (P1 and P2).

Most primates possess the following features (Klein, 1999):

1.Retention of primitive mammalian conditions (i.e. those possessed by early mammals) such as the pentadactyl (5 digits) limb and the clavicle (collarbone). Many mammals have lost some of these digits, e.g. horses (who have a single digit).

2.Grasping hands and feet with highly mobile digits including big toe and usually an opposable thumb.

3.The replacement (in all living species) of primitive mammalian claws with nails (evidenced in the fossil record by flattening of the underlying phalanges.

4.Convergent orbits (eye-sockets) producing overlapping fields of vision and permitting stereoscopic (3d) vision, together with the enhanced neurological apparatus for processing visual information, requiring enlargement of the visual cortex in the occipital and temporal lobes of the brain. The orbits themselves are (in living species) surrounded by a bony ring known as the post- or circum-orbital bar. Higher primates add a bony wall known as the post-orbital plate or septum separating the orbits from the skull behind.

5.The muzzle or snout is shorter than that of most mammals and the sense of smell reduced, with corresponding reduction of the olfactory regions of the brain.

6.A fully bony auditory bulla (middle ear) in which the ventral floor is composed of an extension of the petrosal bone that encloses the inner ear, or a combination of the petrosal bone and the ectotympanic bone or tympanic ring (across which the eardrum is stretched). In other mammals the floor of the bulla generally comprises an independent entotympanic bone; this has been lost in the primates.

7.Reduction of the number of incisors and premolars compared with basal (early) mammals and a relatively simple and primitive cusp pattern on the molars.

8.A unique sulcal (fissure) pattern on the surface of the cerebral cortex of the brain. Also, relative to body size, primates tend to have larger brains than other mammals.

Finally we should ask what is the defining feature of the primate survival strategy – the “killer app” or “unique selling point” to take a couple of crude analogies? Most mammalian (and indeed other) groups have one: the bats combination of flight and echolocation, the rodent ability to gnaw and eat just about anything, the ruminant digestive system and so on. The primate “killer app” is brain-power; primates have large brains for creatures of their size, even in relation to other mammals. Basically the key to primate success has always consisted of being smarter than the competition.

Classifying the Primates
Within the mammals, Primates are grouped with the colugos (Order Dermoptera), tree-shrews (Order Scandentia) and the extinct plesiadapids in Superorder Eurarchonta (“true ancestors”). The Euarchonta is part of a larger grouping, Euarchontoglires, which additionally includes rodents and rabbits.

The plesiadapids were primate-like mammals bearing some resemblance to squirrels. They are now usually classed as order Plesiadapiformes within Euarchonta, though some continue to regard them as a suborder of the primates.

The Primates were traditionally divided between prosimians and anthropoids (or simians). The prosimians comprise four living groups: the lemurs, the lorises, the aye-ayes and the tarsiers.

Lemurs have long tails that they use for balance, but they cannot use them for grasping, unlike monkeys. Their tails are also used as a form of communication, and for male “stink fights”. They have the characteristic primate opposable thumbs and long toes adapted for gripping tree branches, and nails rather than claws on all digits except the second toe of each hind foot, which has a claw used for grooming. Lemurs have a tapetum or reflective layer over the retina, to enhance night vision. Smaller lemurs tend to be nocturnal; the larger ones are diurnal. Studies suggest lemurs have trichromatic colour vision, though it is less sensitive than that of humans. Lemurs range in size from 30 gm to 10kg. They occur in the wild only on Madagascar and are thought to have “rafted” there from Africa after Madagascar broke away from the mainland. Safe from competition, they flourished and diversified.

The lorises are slim diurnal arboreal primates living in tropical central Africa and south and southeast Asia. They have large forward-facing eyes and small ears. The thumbs are opposable and the index finger is short. In common with the lemurs the second toe of the hind legs has a claw for grooming. Their tails are either short or completely absent. They range from between 17 to 40 cm in length and between 0.3 to 2 kg in weight.

The galagos and pottos are grouped with the lorises in the lorids. Like the lorids they are tree-dwelling, but they are nocturnal.

The aye-aye is an endangered species known only from Madagascar. It is the sole member of the Chiromyiformes and is a large (2.5 kg) nocturnal primate. The relationship of the Chiromyiformes to the lemurs and the lorises is uncertain; some make it ancestral to the other two groups.

Tarsiers are small nocturnal primates, now found only in Island South-east Asia, although they were once more widespread. They are characterised by enormous eyes, long hind-limbs and extended tarsus bones (which gives the group its name). They second and third toes of the hindlimbs have grooming claws. They lack a tapetum but they do possess a retinal fovea, suggesting their ancestors were either diurnal or cathemeral (active both day and night).

The taxonomic status of the tarsiers is controversial. They share many key features with the anthropoids, including a hemochorial placenta (i.e. one in which the mother’s blood is in direct contact with the chorion (the outermost of the membranes surrounding the fetus)), a feature not possessed by other prosimians.

Accordingly the tarsiers are now generally grouped with the anthropoids in Suborder Haplorrhini (“dry-nosed”) with the remaining prosimians being placed in Suborder Strepsirrhini (“wet-nosed”). “Wet-nosed” refers to the rhinarium, a moist hairless pad around the nostrils of the nose. This feature can be seen in cats, dogs, mice and indeed it is present in most mammals, including the strepsirrhini, but it has been lost by haplorrhini.

The anthropoids are divided into two groups - the Platyrrhini (“flat-nosed”) - New World monkeys, including marmosets and tamarins; and Catarrhini (“narrow nosed”) – Old world monkeys (cerapithecoids), gibbons, apes and humans (hominoids). The Platyrrhini, the Catarrhini and the anthropoids at large are all believed to be clades or natural groups. The status of the Haplorrhini depends on the affinities of the tarsiers – if any – to the anthropoids. By itself, the term “monkey” does not define a natural group, since the Catarrhini also includes apes and humans. Similarly the apes are not a natural group unless humans are also included.

The extinct adapids and the omomyids are usually assigned to the Strepsirrhini and Haplorrhini respectively. The omomyids are believed to be more closely related to the tarsiers than to other prosimians and to form part of the Haplorrhini, albeit as an outgroup. The adapids are often claimed as ancestors to the lemurs, which seems plausible.

These groupings reflect supposed evolutionary relationships; the supra-ordinal classifications relate to early divergences of the placental mammals, probably occurring in the Cretaceous; the sub-ordinal classifications relate to more recent divergences; for instance the branch between the New and Old World monkeys probably occurred about 40 million years ago (mya).

Trying to represent these relationships within a traditional Linnaean taxonomy is problematic and can only be accomplished by use of a bewildering multiplicity of subdivisions of the main categories. It is far better to try to describe the above groups as clades, or branches on an evolutionary tree.

Origin of the Primates
Primates are of course mammals, a class of vertebrates that evolved from the therapsid or mammal-like reptiles during the Triassic period 220 mya and soon diverged into a number of lines including the therians, which turn includes the marsupials (metatherians) and placentals (eutherians). The placentals and marsupials diverged early in the Cretaceous period 125 mya; the earliest currently known placental is Eomaia scansoria (“climbing dawn mother”) discovered in Liaoning Province, China and described in 2002 (Ji et al, 2002). Early placental mammals were similar to modern animals making up the now-abandoned Order Insectivora, the most primitive mammals (moles, shrews, hedgehogs, etc) but now known to be polyphyletic (i.e. lacking a common ancestor that is part of the same group). These creatures tended to be small and were probably nocturnal – both advantages in a world dominated by dinosaurs.

The long reign of the dinosaurs came to an end at the Cretaceous/Tertiary (K/T) boundary 65.5 mya, almost certainly as a result of an asteroid that struck Earth leaving a massive crater near what is now the town of Chixulub in the Yukatan Peninsula in Mexico. The impact would have triggered tsunami, earthquakes and volcanic eruptions. Material ejected into space by the impact would have re-entered the atmosphere, triggering firestorms across the globe. Finally the dust lofted into the upper atmosphere would have produced an “impact winter” lasting for up to a decade after the impact. Under these conditions, it is little surprise that 50% of the world’s species became extinct.

Nobody doubts that the mammals were the main beneficiaries of this event, but there are three models for their diversification: the Explosive model, the Long Fuse model and the Short Fuse model.

The Explosive model – which is the traditional position - postulates that there was a mammalian “big bang” immediately following the dinosaurs’ disappearance; an evolutionary rush to fill the vacant niches. On this picture, the divergence of the mammalian orders from each other and subsequent diversification within these orders occurred mostly or entirely after the K/T boundary.

The Long Fuse model also places most of the diversification within each mammalian order after the K/T boundary, but in this scenario, the orders themselves diverged from each other well back in the Cretaceous.

Finally, the Short Fuse model postulates even within the various mammalian orders, some diversification had begun to occur over 100 mya, long before the end of the age of the dinosaurs.

These models should not be regarded as mutually exclusive and really mark three points on a continuum of possible models of mammalian diversification.

In 2003 a study was carried out (Springer, Murphy, Eizirik & O’Brien, 2003) applying Bayesian statistics to both genetic and taxonomic data, with constraints based on fossil data. Overall, the results supported the Long Fuse model. The primates diverged from other mammalian groups 85 mya, and the strepsirrhines and haplorrhine diverged 77 mya. The 85 mya date for primate emergence is 17 million years before the earliest known fossil of a possible primate, a creature known as Purgatorius, to which we now turn.

Purgatorius: the first Primate?
Purgatorius, known from a single tooth molar dated to the Late Cretaceous 67 mya and from more comprehensive Palaeocene remains, is the earliest possible primate known from the fossil record. Fossils are known from North America. Although its exact affinities are not known, dental evidence does strongly suggest a link with the primate order. Purgatorius had primitive molars with high cusps, three incisors, a relatively large canine, and four premolars in each quadrant (i.e. on each side of upper and lower jaws). The molars of later primates are more bulbous, none have more than two incisors, and only the more primitive retain four premolars; monkeys apes and humans have lost the two most mesial (i.e. towards the midline). Purgatorius is believed to have been about the size of a mouse or a small rat. It was almost certainly nocturnal, with large eyes adapted for night-vision. It possessed a shrew-like snout and had claws rather than nails. Its diet would probably have consisted of insects and fruit.

Purgatorius survived the K/T boundary event and it was sufficiently generalised in its anatomy to have given rise to the later Eocene primates, but there is no reason to suppose it actually did so.

The Plesiadapids
The Palaeocene (65-56 mya) is the first period of the Cenozoic era, directly following the extinction of the dinosaurs. At that time, the Americas were separated by ocean, but North America was connected to Europe. Climate was much warmer than today, with tropical and subtropical forests in middle latitudes. Palaeocene primates in the fossil record are best known from the Euroamerican land bridge.

The plesiadapids were the most abundant primates (or near-primates) of the Palaeocene and are known from the Palaeocene and Eocene epochs. They ranged in size between mice and squirrels, bearing some resemblance to the latter.

The plesiadapids thrived during the Palaeocene in North America and Eurasia, and some made it into the Eocene, but all had become extinct by the Oligocene, possibly due to competition from rodents. They probably arose in North America, later crossing the land bridge to Eurasia. Like Purgatorius they had claws rather than nails and possessed a generalized, un-evolved skeleton and an elongated skull in which the orbits (eye sockets) were confluent with the temporal region (sides and base) rather than being separated by a bony bar, as is the case with later primates. The affinity of the plesiadapids to later primates – if any – is not known with any certainty. Unlike Purgatorius they possessed dental specialisations including large procumbent central incisors (possibly used to grasp food), a reduced number of lateral incisors, anterior premolars or both (Klein, 1999). No later primate possesses these features, suggesting the plesiadapids died out without issue. Regardless of whether or not you consider them to be true primates, the pleasiadapids are what cladists call an “outgroup” in relation to (other) prmates, i.e. less closely related to other members of a clade.

Adapids and Omomyids
The Palaeocene is followed by the Eocene (56-34 mya). Early in this period the land connection between Europe and North America was broken; however the mild climate persisted. Forest vegetation, increased rainfall and hotter conditions had spread from the equator to the poles. Two diverse primate groups – the adapids and the omomyids - become very common in the early Eocene fossil records of North America, Europe, Asia and possibly Africa where Altiatlasius koulchii, known from 60 million year old teeth discovered in Adrar Mgorn in Southern Morocco, has been assigned to the omomyids. Both groups possessed features associated with living primates such as grasping hands and feet with digits tipped by nails instead of claws, and a complete postorbital bar. There was a shift in emphasis from sense of smell to vision.

The adapids tended to be relatively large, with a typical body mass of 1kg. Characteristic features included small orbits, suggesting a diurnal lifestyle and cheek teeth adapted for diets consisting of leaves and fruit. Postcranial remains (i.e. those below the cranium) suggest an arboreal lifestyle. They resembled lemurs but lacked some of the specialisations of living lemurs and lorises. They retain four premolars on each side of the jaw, whereas lemurs have only three. They had generalised lower incisors and canines; in lemurs these are elongated and protruding to form a dental comb. That the adapids were ancestral to the lemurs is widely but not universally accepted. That they were ancestral to the anthropoids seems less likely, though it cannot be ruled out.

By contrast the omomyids were smaller (below 500gms), with much larger orbits, suggesting a nocturnal habit. Their cheek teeth were adapted for a diet primarily of insects. They possessed elongated tarsal bones, similar to those of the tarsiers. It is a popular view that they were ancestral to the tarsiers and/or the anthropoids; again, though, this is not universally accepted.

Were early primates diurnal?
The commonly-held view that early primates were nocturnal rests largely on the fact that the majority of living prosimians are so, and the large orbits of many fossil forms, suggesting that they were also.

We have already seen that there is reason to believe that the tarsiers evolved from diurnal ancestors, and this is supported by a study of the gene sequences of opsins in primates, which rejects the nocturnality – or at least exclusive nocturnality - of ancestral primates.
Opsins are light-sensitive proteins found in retinal photoreceptor cells. Trichromatic or colour vision requires three types of opsin, sensitive to short, medium and long wavelengths. However colour vision is not is particularly useful for nocturnal animals, and has been found that in nocturnal animals either the genes coding for short wavelengths or those coding for medium/long-wave opsins rapidly pick up deleterious mutations, rendering the opsins themselves non-functional and giving the animal only monochromatic (“black-and-white”) vision. Because the “bad” opsin genes do not in such cases affect the organism’s survival, there is no Darwinian natural selection acting to eliminate them.

For any species, this mutation would be expected to occur at the same rate across successive generations, and on the nocturnal picture the opsin genes in all nocturnal primates would be expected to have undergone similar degrees of deleterious mutations, reflecting similar times of divergence from the last common diurnal ancestor (presumed not to be a primate).

However this prediction was not borne out by the study, which showed considerable variation in the degree of genetic defects found across a range of prosimians, indicating different time periods of deleterious mutation for different lineages, and suggesting different diurnal ancestry for each.
This in turn implies that the common primate ancestor of all of these lineages must have been diurnal, unless each lineage independently went through a phase of diurnality, before reverting to nocturnality, which seems unlikely (Tan, Yoder, Yamasita & Li, 2005).

Origin of the Anthropoids
As we have seen, the Springer, Murphy, Eizirik & O’Brien study gives a date of 77 mya for the divergence of the Haplorrhini from the Strepsirrhini. Other estimates range from 90 to 63 mya.
The origins of the anthropoids within this group are incompletely understood, with four competing theories of anthropoid phylogeny: 1) they evolved from Eocene adapids; 2) they evolved from Eocene omomyids; 3) they evolved from tarsiers; 4) they diverged from other haplorrhines early in the Cenozoic, and form a sister group to the omomyid/tarsier clade.
There are also four major competing views concerning the geographic origins of the anthropoids: 1) anthropoids originated in the circum-Tethyan region (the shores of the Tethys Sea, an ocean separating the supercontinents of Laurasia and Gondwana); 2) anthropoids originated on the Asian continental landmass; 3) anthropoids originated as part of a southern continental fauna, centred on Indo-Madagascar; or 4) anthropoids originated in Africa.

A review of existing data and theories about anthropoid origins was published in 2005 (Miller, Gunnell & Martin, 2005). Morphological, molecular and biogeographic evidence was considered. The review rejected ancestry with any known primate group. It claimed the anthropoids have existed as long as any known primate group, and that the time-depth is too great for their ancestry to be reliably determined, though its authors did not rule out one of known groups could be more closely related than the others.

This is a rather extreme view: the last phylogeny of the four above seems to be a less extreme position (Beard, K. C., Krishtalka, L. & Stucky, R. K., 1991). On this picture, there is a relatively early split in the Haplorrhini between the anthropoids and the common ancestor of both the omomyids and the tarsiers.

The Miller, Gunnell & Martin review also considered geographic origins of the anthropoids, and came down in favour of either an African or Indo-Madagascan origin.

Eosimias: Dawn Monkey from China
Currently, the earliest known anthropoid is Eosimias sinesis (“dawn monkey from China”), which is believed to have lived 45 mya. A fragment of a lower jawbone and foot bones were unearthed in China in the 1990s by joint American-Chinese expeditions led by Dr. Christopher Beard of the Carnegie Museum of Natural History. Eosimias is believed to have weighed no more than 100 gms, about the size of a pygmy marmoset. Beard and his colleagues claimed the remains suggest a Middle to Late Eocene emergence in eastern Asia of the mosaic of traits leading from primitive to anthropoid physiology. It shares derived features with undoubted anthropoids, including a 2-1-3-3 dental formula, a single-rooted anterior lower premolar (P2), shortening and crowding of the third and fourth premolars (P3 and P4) and labial expansion of the crowns. However, the two halves of the jawbone are not fused at the symphysis (cartilaginous joint), unlike all later anthropoids.

The anthropoid status of Eosimias was supported by a study published in Nature in 2000. A parsimony analysis of eleven tarsal characters using the PAUP 4.0 (Phylogenetic Analysis Using Parsimony) computer program suggested that Eosimias is a sister group to other anthropoids (Gebo, Dagosto, Beard, Qi & Wang, 2000).

Later Eocene Anthropoids
From Myanmar (Burma) come fragmentary jaws believed to date to 44-40 mya, representing at least two possible anthropoid species – the gibbon-sized Amphipithecus mogaungensis and the less well-known Pondaungia cotteri.

Amphipithecus had a number of features linking it with the anthropoids: the jawbone was deep compared with molar crown height and remained deep all along the jaw (in prosimians it is shallower, especially towards the front); the jawbone was fused at the symphysis (unlike Eosimias) and reinforced by an inferior and a superior transverse torus (a horizontal shelf-like thickening of bone; when this feature is present in prosimians they have only the inferior transverse torus); the second molar was parallel-sided (in common with anthropoids) and not narrowing towards the front (unlike the prosimians).

In common with Eosimias the dental formula is 2-1-3-3. The molar crowns were relatively flat, with low blunt cusps, suggesting a diet focussed more on leaves and fruit and less on insects than is typical for prosmimians; its premolar morphology was close enough to that of Eosimias to suggest descent; its overall form was sufficiently generalised for it to be ancestral to both the Catarrhini and the Platyrrhini (Klein, 1999).

Fossils of the Fayum Depression, Egypt
One of the most productive fossil sites for early anthropoids is the Jebel Qatrani Formation in the Fayum Depression, near Cairo, Egypt. The sheer diversity of the Fayum taxa is strong evidence for an African origin and early radiation for the anthropoids. It also supports the greater time depth for the anthropoids than was once supposed, as suggested in Miller, Gunnell & Martin review.

The site was originally attributed to the early Oligocene, but is now believed to straddle the Eocene/Oligocene boundary, 34 mya. Late Eocene material includes partial jaws, skull fragments and limb bones and has been assigned to four anthropoid genera (Catopithecus, Proteopithecus, Serapia and Arsinoea), all believed to have been small, weighing less than 900 gm, roughly the size of a squirrel monkey. Their premolars and molars resemble those of later Oligocene anthropoids.

A nearly complete skull of Catopithecus reveals clear anthropoid features including fused frontal bones, a postorbital plate separating the orbit from the braincase and an ectotympanic bone fused to the margin of the auditory bulla. However its brain was smaller than that of a modern anthropoid of the same size. Proteopithecus retained the 2-1-3-3 dental formula of Amphipithecus, the formula still found in living platyrrhines, meaning it may lie near the common ancestry of both the platyrrhines and the catarrhines. On the other hand Catopithecus has lost a premolar and has the 2-1-2-3 found in later catarrhines.

Both Catopithecus and Proteopithecus are tentatively assigned to the propliopithecids, a catarrhine/proto-catarrhine family known mainly from the Oligocene. However the affinities of these taxa to later groupings are very tentative and the 2-1-3-3 dental formula of Proteopithecus makes such an association questionable.

The Platyrrhine/Catarrhine split
New World monkeys show up in the South American fossil record from 25 mya. Nobody knows for certain how they got there but rafting from Africa likeliest explanation. This theory suggests that the ancestors of the New World monkeys (and presumably other animals) were swept out to sea by flash floods, together with mats of vegetation on which they were able to survive until the currents brought them ashore in South America.

Although it might seem more feasible to suggest that the New World monkeys reached South and Central America via North America, there are two objections. Firstly there is no fossil evidence to suppose that any anthropoids ever lived in North America prior to the arrival of humans; secondly the Americas were still separate and actually further apart than South America was from Africa and South America. Furthermore there were probably chains of islands stretching between the two continents, so series of shorter rafting events could have taken place. Notably some rodents are also believed to have reached South America from Africa.

Estimates based on molecular data suggest the split between the Platyrrhine and Catarrhine occurred approximately 40 mya. Although the platyrrhines are believed to have originated in Africa, fossil evidence is lacking. Proteopithecus has many features resembling both fossil and present-day platyrrhines, but these appear to be pleisiomorphies, i.e. features shared with anthropoids predating the platyrrhine/catarrhine split (Miller & Simons, 1997).

Into the Oligocene
The Oligocene (34-23 mya) is the third period of the Cenozoic Era. At the transition to the Oligocene global temperatures dropped sharply as the configuration and topography of the continents changed, altering oceanic and atmospheric circulation. The cooler, dryer conditions resulted eventually in the disappearance of subtropical forest from middle latitudes. It was during this period that the promsimians went into decline and became confined largely to nocturnal niches, suffering from both loss of habitat (in Europe and North America) and competition from the anthropoids (in Africa and Asia). Only in Madagascar – which the anthropoids never reached – did the prosimians continue to flourish.

Roughly 1000 primate specimens have been recovered from the Oligocene layers of the Fayum, of which all but a handful are anthropoids. Twelve species in six genera are generally recognised: Qatrania, Apidium, Parapithecus, Propliopithecus, Aegyptopithecus and Oligopithecus. These are grouped into the parapithecoids (Qatrania, Apidium and Parapithecus) and the propliopithecoids (Propliopithecus, Oligopithecus and Aegyptopithecus). Not all lived at the same time and some may have evolved from others.

By the standards of present-day anthropoids, the Oligocene Fayum taxa were small, ranging from 300gms for Qatrania to 3-4 kg (Parapithecus) up to 5.9 kg (Aegyptpithecus, some species of Propliopithecus). They were still larger than any modern insectivorous primates, suggesting they were mainly fruit or leaf eaters. The majority had short molar shearing crests, suggesting they were fruit eaters. Most were probably arboreal (by analogy with similar-sized living primates). The limb bone morphology suggests they were either quadruped-climbers (Propliopithecus and Aegyptopithecus) or quadruped-leapers (Apidum).

The parapithecoids possess the 2-1-3-3 dental formula of platyrrhines. They are probably basal to the anthropoids as a whole: their origins predating the platyrrhine/catarrhine split. It seems quite likely that they represent a separate and extinct branch of the anthropoids and are not ancestral to either the platyrrhines or the catarrhines.

The propliopithecoids have a 2-1-2-3 dental formula, suggesting a link with the catarrhines. Skull and postcranial evidence, in particular from Aegyptopithecus, suggests that they lie close to the ancestry of both the Old World Monkeys and the hominoids, but predate the split between these two groups.

Cerapithecoids and Hominoids
The penultimate split in the primate line is that between the cerapithecoids (Old World Monkeys) and the hominoids (apes and humans). Just when the split occurred is not known for certain due the poor fossil record. However the split must have occurred between the time of Aegyptopithecus (33 mya); and that of the first generally accepted apes Morotopithecus (21 mya) and Proconsul (20 mya). A commonly-accepted date is 23-25 mya (Late Oligocene/Early Miocene), based on molecular data, though one study using a technique known as maximum likelihood-based quartet analysis places it much further back, at approximately 30 mya in the Early Oligocene. Maximum likelihood-based quartet analysis is a computer-intensive statistical technique that has found widespread use in calculating divergence times (Steiper, Young and Sukarna, 2004).

The Early Miocene
The Miocene (23 – 5.33 mya) is the fourth period of the Cenozoic Era. By this time the configuration of the continents was approaching that today, and many familiar geographic features formed as a result of continental collisions during the Miocene. These included the Himalayas, the Tibetan Plateau, the Ethiopian highlands and the Rift Valley. The Ethiopian highlands interrupted the eastwards flow of rain, creating a rain-shadow across East Africa, which saw a significant rainfall reduction. This effect was exacerbated by the uplift of the Himalayas and the Tibetan Plateau.

From the earliest Miocene, 23 million years ago, the rainforest belt covering Africa had been breaking up into distinct ecological niches with increasing patches of woodland/grassland interrupting the rainforests.

As Africa’s northward drift brought it into contact with Eurasia, the Tethys Sea closed, causing southern Eurasia to become cooler and dryer. Equally important, the new land connections permitted faunal exchange between Africa and Eurasia, and among the migrants were the hominoids, who radiated through the forests of Eurasia, from Spain to China.

In eastern Africa, primates inhabited tropical forest and woodland. Most were hominoids with cerapithecoids being infrequent. Cerapithecoids only predominated in the less forested regions such as northern Africa.

A number of early Miocene hominoid species are known from fossil deposits in eastern Africa. The best known is Proconsul but at least five other genera are known: Dendropithecus, Micropithecus, Morotopithecus, Afropithecus and Turkanapithecus.

The ape-like Proconsul, discovered in 1909 and named in 1931, appeared in Kenya about 20 mya and possessed some Old World monkey features such as short forelimbs and a deep, narrow chest. Its forelimbs were adapted for walking on palms rather than the knuckle-walking of modern chimps and gorillas. In common with modern apes it lacked a tail and had a slightly larger brain, relative to its size, than a monkey. Proconsul was a forest-dwelling arboreal quadruped, spending much of its time in the trees. Its facial anatomy and low-cusped thin enamelled molars suggest that its diet consisted largely of soft fruit. It lacked the enlarged fruit-peeling incisors of chimps and orang-utans and the high-cusped leaf-chewing molars of gorillas. It was sufficiently generalised to be close to the common ancestry of all three. Proconsul comprised 3-5 species, ranging in size from 11 kg (roughly the size of a gibbon) to 87 kg (orang-utan sized). The name “Proconsul” is a reference to it having evolved before chimpanzees; “Consul” was a common name for chimpanzees at that time, including one at London Zoo.

Out of Africa – and back again!
Kenyapithecus africanus, a hominoid that appeared around 16-15 mya, is often touted as the direct ancestor of the great apes and humans. Its more immediate descendents could have included a number of later Eurasian Miocene hominoids: Ouranopithecus, Sivapithecus and Gigantopithecus. Kenyapithecus had a robust jawbone, enlarged upper premolars and thick enamel – features that are certainly steps in the direction.

By this time, beginning 17-18 mya hominoids were migrating across the newly-established land bridge into Eurasia where, as already noted, they flourished. At least seven genera probably existed: Dryopithecus (14-8 mya, known from central and western Europe), Pliopithecus (16-11 mya, known western and south-central Europe and southern China), Ouranopithecus a.k.a. Graecopithecus (9.6-8.7 mya, known from Greece), Sivapithecus (12.5-7 mya, known from Siwalik Hills on India-Pakistan border and in Turkey), Gigantopithecus (6.3-0.5 mya, Siwalik, western China, Vietnam [largest primate ever, bigger than a gorilla]), Lufengpithecus (8-7 mya, known from Lufen in southern China) and Oreopithecus (9-8 mya, known from Italy).

These apes ranged in size from gibbons to chimpanzees, though the aptly-named Gigantopithecus was even larger than a gorilla and is the largest primate ever to have lived. They were further evolved in the direction of modern apes. Dryopithecus, for example, had a shortened inflexible lumbar vertebral (waist) skeleton, broad flat thorax (chest), scapulae (shoulder-blades) behind the thorax (rather than alongside), long arms that could rotate around the shoulder joint, implying upright (orthograde) posture (as opposed to prograde), and able to hang below branches or climb hand over hand – it is the oldest hominoid for which this characteristic ape-like posture and locomotion can be implied.

Others, such as Ouranopithecus had thick enamel, permitting it to eat nuts, seeds, tubers and other hard grit encrusted food, which became common in relation to fruit as woodland replaced forest. Faunal remains suggest it occupied open woodland and savannah and had to spend significant amounts of time on the ground to get at its preferred foodstuffs. Its teeth resemble those of the later australopithecines, suggesting it is close to the line leading to humans. Unfortunately no post-cranial remains have been found.

Sivapithecus also had thick enamel and lived in open woodland. It had many features in common with orang-utan and is thought to be ancestral. If so, it suggests orang-utans had split from the line leading to African hominids by 12 mya.

If any of these Eurasian apes was the common ancestor to modern-day gibbons, great apes and humans, how did we end up with gibbons and orang-utans in Asia, and gorillas, chimps and humans in Africa? The poor hominoid fossil record in Africa after 13 mya has led some to propose scenarios in which hominoids left Africa, but their descendants later returned.

One possible scenario is that the ancestor of the gibbons left Africa, leaving behind the ancestor(s) of orang-utans, chimps and gorillas. Subsequently the ancestor of orang-utans dispersed to Asia.

A second scenario, involving fewer assumptions, is that the ancestor of all of the above (possibly Kenyapithecus) dispersed out of Africa and gave rise (via one of the genera described above) to the gibbons and great apes in Eurasia. One group later moved back to Africa and begat the gorillas, chimps, and humans. This move back to Africa would have happened after the gibbon/great ape divergence, but before the emergence of Sivapithecus. This “Out of Africa and back again” scenario seems highly plausible.

If this second scenario is accepted, then the immediate ancestor of the hominids emerged from Eurasia 14-15 million years ago and joined a general faunal migration into Africa, taking advantage of the new cooler conditions at the expense of the endemic fauna.

Finally, about 6 million years ago, the line diverged again, with one line leading to chimps and the other to the australopithecines and, ultimately, to humans.

Nakalipithecus nakayamai
However recent discoveries (Kunimatsu, Yutaka et al., 2007) have cast doubt on the “Out of Africa and back again” scenario. A jawbone and teeth recovered from Nakali, Kenya have been assigned to a new genus of great ape, Nakalipithecus nakayamai. N. Nakayamai is described as a large hominoid with dental size corresponding to female gorillas and orang-utans and it has similarities to Ouranopithecus. It appears to be slightly older than Ournaopithecus (9.9-9.8 mya, versus 9.6-8.7 mya). Another fossil great ape, Chororapithecus abyssinicus has also recently been discovered in Ethiopia (Suwa et al, 2007).

These findings together with the long-established existence of a third Late Miocene hominid, Samburupithecus kiptamali, discovered in 1982 in the Samburu Hills, northern Kenya, weaken the view that hominoids disappeared from Africa in the late Miocene. Although it is not necessarily the case that any of these apes are the last common ancestor of humans and African apes, it may well be the case that they are close relatives.

Clearly further fossil evidence is required, and all that can safely be said at the present time is that the matter is far from settled.


Beard, K. C., Krishtalka, L. & Stucky, R. K. 1991: First skulls of the early Eocene primate Shoshonius cooperi and the anthropoid–tarsier dichotomy. Nature (349), 64–67 (1991).

Cameron, D and Groves, C 2004: Bones, Stones and Molecules: “Out of Africa” and Human Origins, Elsevier Academic Press.

Colbert, E and Morales, M 1991: Evolution of the Vertebrates (4th edition), John Wiley & Sons, Inc.

Gebo, Dagosto, Beard, Qi & Wang 2000: The oldest known anthropoid postcranial fossils and the early evolution of higher primates, Nature (404) 16 March 2000 pp 276-278.

Groves, C 1991: A Theory of Human and Primate Evolution, Clarendon Press Oxford.

Ji et al 2002: The earliest known eutherian mammal. Nature (416), pp 816-822.

Klein, R 1999: The Human Career (2nd edition), University of Chicago Press.

Kunimatsu, Yutaka et al. (2007): A new Late Miocene great ape from Kenya and its implications for the origins of African great apes and humans. PNAS 104(49) pp.19220–19225 (December 4, 2007)

Levin, R and Foley, R 2004: Principles of Human Evolution (2nd edition), Blackwell Publishing.

Miller, Gunnell & Martin 2005: Deep Time Depth and the search for Anthropoid Origins, Yearbook of Physical Anthropology 48:60–95 (2005).

Miller, E & Simons, E 1997: Dentition of Proteopithecus sylviae, an archaic anthropoid from the Fayum, Egypt, PNAS Vol. 94, pp. 13760–13764, December 1997

Springer, Murphy, Eizirik & O’Brien 2003: Placental mammal diversification and the Cretaceous-Tertiary boundary, PNAS February 4, 2003 vol. 100 no. 3 1056-1061.

Steiper, M, Young, N and Sukarna, T 2004: Genomic data support the hominoid slowdown and an Early Oligocene estimate for the hominoid–cercopithecoid divergence PNAS December 7, 2004 vol. 101 no. 49 17025.

Suwa, Kono, Katoh, Asfaw & Beyene 2007: A new species of great ape from the late Miocene epoch in Ethiopia, Nature (448), 23 August 2007, pp 921-924.

Tan, Yoder, Yamasita & Li 2005: Evidence from opsin genes rejects nocturnality in ancestral primates, PNAS October 11, 2005 vol. 102 no. 41 14715.

© Christopher Seddon 2008

Friday, 21 March 2008

Sir Arthur C. Clarke (1917-2008)

Late on Tuesday, I had just finished posting an entry on this blog (a science-fiction story, ironically) and as I often do, I took a last look for the day at the BBC website where I learned that Sir Arthur C. Clarke had died at the age of 90.

As a life-long SF enthusiast, I was familiar with Clarke’s short stories long before I was familiar with him by name. At the age of ten, much of the science fiction in the children’s section of the local library was in the form of multi-author anthologies and the first work by Clarke that I read would have been either Breaking Strain or Hide and Seek (I think they both featured in the same volume).

Breaking Strain is one of the best character-driven short stories ever written – a space freighter is struck by a small meteorite, which causes most of its oxygen supply to be lost into space. Enough oxygen remains to last the two-man crew 20 days – but the ship is still 30 days from its destination. However one doesn’t have to be Einstein to realise that the oxygen could last one man for 40 days...

Here was surely a superb opportunity for a movie in the vein of Lifeboat or Strongroom, but sadly when a film version appeared in the 1990s it was dire: Grant and McNeill (the original crew, whose first names we never learned) were joined by four other shipmates (including the obligatory hot chick), who waste very little time in starting to kill each other. This is in complete contrast to the original in which Grant and McNeill are portrayed as two men of sound if contrasting character, who are gradually driven to extremities by their situation.

The movie’s title was changed to Trapped in Space – something more appropriate for an episode of Thunderbirds.

I recall reading Hide and Seek while my father looked round a house we subsequently moved to. Presumably we had gone via the library: it was more or less standard procedure on a Saturday morning. In this story, the one man crew of a scout-ship takes refuge on the Martian moon of Phobos and manages to elude a pursuing warship until reinforcements arrive.

By 14 I’d graduated to the adult section of the library and duly encountered Arthur C. Clarke’s novels – by the end of 1971 I must have read most of them. Three that stood out for me were Against the Fall of Night (I didn’t come across the expanded version, The City and the Stars, until later - like Clarke himself I have never been able to make up my mind which version I prefer), Childhood’s End and of course 2001: A Space Odyssey.

Strangely enough I did not see 2001 when it came out and in an era before DVDs or even VHS I had to wait until its second cinematic release in the late 1970s. So for many years I was only familiar with the novel version.

The following is a piece I posted on my personal website back in 2000 in an attempt to promote my own rather more modest career as a science fiction writer (square [] brackets denote my later comments):

In just a few months from now, the best-known date in science fiction history (along with 1984) will be upon us.

2001 is undoubtedly Sir Arthur C. Clarke's best-known work, if not quite his best. The novel cannot really be separated from the late Stanley Kubrick's landmark film, as the two were written in conjunction. The book version is not a "novellization" of the movie, nor is the movie version the "film of the book". It says much for the genius of both Clarke and Kubrick that the two versions stand on a par - you cannot really say that one is better than the other, and they are both classics in their own medium.

2001 is based upon a 1948 short story, The Sentinel, which appears in the collection Expedition to Earth (which additionally features the Hitchcock-esque classic Breaking Strain, another childhood favourite of mine, Hide and Seek and the cautionary tale Superiority) [I added these remarks to try and sell Expedition to Earth and other SF books from my site via Amazon, but I don’t think anybody even read the review let alone used the Amazon hyperlinks]. The Sentinel tells of a crystal pyramid (rather than the familiar monolith) found on the moon. It takes 20 years to find a means of breaking through the force-field that surrounds it, and the artefact is destroyed in the process. The narrator speculates that it has been left on the moon in prehistoric times to await the arrival of man, patiently signalling that nobody has found it. Once found and put out of action, it will alert its creators to the fact that man has mastered the secret of space travel.

2001 begins four million years ago, with the appearance of a monolith on Earth which stimulates the development of a group of primitive pre-human hominids (Australopithecus?). The sight of it, the Sun and a crescent moon will be a recurring theme in the movie. The hominids are starving to death in the midst of plenty, with no inkling that the herds of pigs roaming unsuspectingly close by represent a very convenient source of food. The monolith changes that and in a dramatic example of conceptual breakthrough, a hominid visualises how an animal bone can be used to kill the pigs.

The animal bone can be used for killing things other than pigs. The opening scene of the movie ends dramatically when the hominid leader uses it to club to death the leader of a rival group, thus giving the latter the highly dubious honour of becoming the first ever casualty of a war. Unaware of the unfortunate trend he has just started, the hominid leader triumphantly hurls the bone up into the air. It circles round and is replaced by the image of an orbital satellite. The serene "dance of the machines" and its Blue Danube accompaniment contrasts sharply with the brutality of the previous scene [and with the 11 September terrorist attacks, which in our universe at least, was the event for which the year 2001 will be chiefly remembered].

2001 was not the first science fiction movie to use classical music [as opposed to a dedicated score], but none before or since has done so a tenth as effectively.

There is a minor but amusing difference between the two versions at this point. In the movie, we see Floyd's space shuttle has to spin on its central axis in order to dock with the wheel-like space station; in the book the docking section of the wheel does not rotate and the shuttle is able to dock without it and its occupants being "whirled disastrously around", as Clarke puts it!

After an interlude aboard a space station that is a masterpiece of 'Sixties interior decor, Floyd's journey to the moon resumes aboard an Aries-1B moon shuttle; after landing at Clavius Base he is conveyed by surface transport to Tycho, where the Monolith awaits. As he and his colleagues contemplate the enigmatic ebony-black slab that has been identified by its anomalous magnetic signature, their helmet radios are filled with a piercing burst of sound. It's not a malfunction - the radios are picking up a signal emitted by the Monolith as the Sun shines on it for the first time in three million years. We see again the mystical alignment of monolith, Sun and a crescent Earth (replacing the crescent moon seen earlier). Unfortunately, the scene is a howler in more ways than one - just minutes earlier, we saw Floyd's surface transport skimming across a lunar landscape lit by a gibbous Earth!

Both versions now switch to the USS Discovery, en route for Jupiter. But where as in the film the king of the planets is the final destination, in the novel the ship does not stop there but uses the principle of "gravity assist" to speed her passage to her final destination - Saturn. This is exactly the same techniques used just a few years later by NASA to send Pioneer 10 and the two Voyager probes to Saturn. The events aboard the Discovery as HAL turns against David Bowman and Frank Poole are too well known to be worth recounting her. But while in the movie HAL refuses to let David Bowman back aboard the ship with the famous, almost apologetic "I'm sorry, Dave, I'm afraid I can't do that", in the novel, the maverick computer simply opens the hangar - which does avoid the obvious question as to why Bowman left his helmet behind in the first place.

The movie version is, however, truer to one of Clarke's pet ideas, that of an astronaut trying to cross between two spacecraft without a spacesuit. Clarke first explores the idea in Earthlight, when the Earth liner Pegasus goes to the aid of the stricken Federation warship Acheron and manages to take off most of her 120-strong crew, despite there being a grand total of five spacesuits aboard - a humanitarian action that shames the two warring sides into signing a peace treaty. The idea crops up again in Take a Deep Breath, one of a series of linked stories set aboard a space station and originally written for the Evening Standard in 1957, when four men have to be rescued from a compartment that has come loose from the rest of the station.

In their very different but equally effective ways, the novel and movie versions follow David Bowman's mind-boggling jouney through the Stargate (located in orbit around Jupiter in the movie, but on the surface of the Saturnian moon of Japetus in the novel), where he is transformed into a higher but child-like lifeform, capable of returning to Earth in literally no time at all.

The idea of a higher but child-like lifeform is another recurring Clarke theme - in Childhood's End, mankind is reborn as part of the Overmind with the assistance of the Overlords, a race of satanic-looking beings who are actually benign "cosmic midwives". And in Against the Fall of Night/The City and the Stars, the restless Alvin encounters Vanamonde, a creature of pure mentality that is still millions of years away from maturity.

It is a simple but very effective tribute to Clarke's genius that his unique writing style more than compensates for the absence of the movie's breathtaking visual effects. As for the movie, it is still stunning after over three decades, with the real 2001 just around the corner.

Perhaps it would have been better if things had been left with the Star Child contemplating the planet Earth, but even Sir Arthur C. Clarke is only human and the temptation to write a sequel must have been overwhelming. As a reader, I have to confess I couldn't get hold of a copy of 2010: Odyssey Two fast enough. It, 2061: Odyssey Three and 3001: The Final Odyssey are all extremely readable (as one would expect from Clarke), all contain fascinating ideas of which the most interesting are the ill-fated Chinese landing on Europa and the discovery of life there, an asteroid-sized diamond left over from the destruction of Jupiter and a very believable account of life at the dawn of the Fourth Millennium.

Eight years after I wrote this piece it is probably worth pointing out that Clarke and Kubrick were also responsible for the pronunciation of 21st Century years – Two Thousand and One rather than Twenty Oh One. The latter would have been consistent with the way years were pronounced in the last century, thus 1999 was pronounced Nineteen Ninety-Nine: only legal documents would have written it as Nineteen Hundred and Ninety-Nine. At some stage we will probably revert to the previous convention, I suspect no later than 2066 if only because the most famous date in English history has always been pronounced Ten Sixty-Six and not One Thousand and Sixty-Six, though I’m unlikely to be around to find out .

Until the 1970s Arthur C. Clarke’s stories regularly featured faster than light travel, which according to Einstein’s Theory of Relativity is impossible. To quote Clarke’s First Law: When a distinguished but elderly scientist states that something is possible, he is almost certainly right. When he states that something is impossible, he is very probably wrong.

In one of his non-fiction works, Clarke took a swipe at the Principle of Equivalence, which states that there is no way to tell the difference between a gravity field and the effects of acceleration. Clarke claimed that this must be incorrect because a gravity field obeys the Inverse Square Law (the field weakens as the square of the distance) whereas the effects of acceleration is uniform. Therefore “there might be a hole through which we can push our trans-photic [faster than light] ship”. Arthur C. Clarke was a far better physicist than I am (he gained a First from King’s College, London whereas I only managed a 2.2 from the same institution), so I assume this remark was tongue-in-cheek as even I can see the flaw in this argument.

Clarke remained a prolific writer during the 1970s but it is interesting that his writing then underwent a paradigm shift in that he rejected the possibility of faster than light travel and it did not feature in any of his subsequent stories.

The flood of thought-provoking ideas continued unabated however. Imperial Earth – set 300 years in the future - featured a particularly cool gadget called a Mini Sec which was basically what we’d now call a PDA. At the time, I wanted one but didn’t expect to be able to own one in my life time. In fact, I only had to wait ten years before the first PDA – the Psion Organizer – had made its appearance. However the Mini Sec was based on the then cutting-edge pocket calculator: Clarke failed to anticipate the touch-sensitive screen. He also predicted that the chord-keyboard featured in the late 1980s Microwriter AgendA would come into standard usage, but it never really took off.

Clarke’s more successful predictions include mobile phones and communication satellites (though he anticipated that they would need to be manned) and to this day the geostationary orbit is named the Clarke Orbit. The space elevator remains unrealised, but its time will come.

Sir Arthur C. Clarke has said that he would prefer to be remembered as a writer and it thus that he will be largely remembered. However he was much more than just a science fiction writer and it is certainly safe to say that if he had never written a single work of science fiction, he would still have been a household name.

© Christopher Seddon 2008

Tuesday, 18 March 2008

The Face of Noah

In the cramped confines of Pathfinder One, Lycurgus Burrell was ready to become the first man in space. For the first time he noticed the fresh tang of his own sweat. He was uncomfortably aware that he was sitting on top of enough kerosene and liquid oxygen to blow him all the way to the Moon. Once again he found himself staring out through the tiny window in front of him, which showed nothing but bright blue skies.

Outside, tinny loudspeakers proclaimed the countdown to be into the last three minutes and urged clearance of the launch area. In a short while, he'd see the inky blackness of space. In less than half an hour, he'd see the Moon go rushing past at three and a half miles per second.
An hour from now - assuming he wasn't dead - he'd be back on the ground. This was the culmination of a quarter of a century, during which he had been labelled variously as a visionary, a heretic - and a fool pure and simple.

And even he didn't know which was right...

Like a misshapen blood-orange, the Moon shot up above the western horizon. In less than a minute, its hue had faded to a leaden off-white. Lycurgus Burrell stared absent-mindedly at the shadows of the nearby line of trees, marching in step with the Moon's rapid progress across the heavens. Then the light dimmed, briefly attenuated as the Moon passed behind the sinister plume rising above Mount Erebus.

He could still faintly hear pop music and smell wood-smoke from the campsite, half a mile away.

"An archaeological dig led by a mad middle-aged hippie!" he said disgustedly. "What am I doing here?" But the disgust was directed at himself, and the question purely rhetorical.
Lycurgus stared up at the almost-full Moon. The enigmatic Face of Noah was well placed for observation, on the Moon’s eastern limb. Astronomers claimed there had once been a time when the whole of the feature could clearly be seen from Tellus, but changes in the Moon’s orbit were gradually carrying it out of view.

Why had it given rise to a Biblical story? Presumably because of a coincidental likeness to a human face. The idea that men had been to the Moon in Biblical times and carved the feature there was too ludicrous for words.

Dr. Auerbach wanted to go to the Moon for real in the here and now and he, Lycurgus Burrell, could have been a part of that quest. But he’d blown it big time.

“What a bloody mess!” he said aloud.

"Gus? Is that you?" said a voice behind him. It was that of Olwen Rees - the mad hippie herself.

Mildly curious, he turned round. "Professor?"

The tall square-jawed archaeologist favoured him with a sympathetic smile. The quartz crystal she wore as a pendant glinted in the moonlight. Doubtless news of his disastrous move for Catrina was all over the camp by now. Had she come looking for him? It was an oddly appealing thought, but the backpack she was wearing suggested some other agenda.

"Not partying?" she enquired.

"I'm not in a party mood," Lycurgus admitted. "You're going somewhere," he ventured.

"This modern pop's hardly my scene," Olwen said.

"Are you planning on getting so far away from the music you need a backpack, Professor?" Lycurgus persisted.

Olwen shrugged. "Dr. Potter's called me on the R/T. He reckons Erebus is about to blow its top. There'll be accompanying quakes and the works. The quake that opened the fissure was only a prelude."

"When’s this going to happen?"

"Any time within the next three days. Potter's getting his team out at first light and he strongly suggested we pull out too."

Lycurgus felt a glimmer of hope. "What are we going to do?"

"I'm taking Potter's advice."

Praise be, Lycurgus thought. Now he could go home and put this humiliating experience behind him. Maybe he could take up that placement with the NLIS after all.

"Why couldn't the bloody thing have waited another week?" Olwen bemoaned. "A few days at the site, just a few poxy days! That's all we'd have needed."

The backpack!

"Professor, if this is true, I don't think going to the site on your own is a particularly good idea."

"I've about eight hours before sunrise and it's only another couple of hours walk to the site. That'll give me four hours at the site - it's better than nothing."

"Are you crazy?" Lycurgus exclaimed.

"Gus, three days from now at most the Novacastra Diggings will have gone forever, and with it any chance to investigate what Potter's team claim they saw."

"They've got photographs, haven't they?" Lycurgus was surprised how keen he was to dissuade her from going.

But Olwen was unimpressed. "Potter and his team are geologists, not archaeologists. They wouldn't have a clue what to photograph. We can safely assume that anything they have got will be of little value."

Lycurgus found himself offering to accompany Olwen.

"T minus one minute," Robert Auerbach announced over the radio.

Burrell recalled the Catrina episode with wry amusement and the benefit of twenty-five years of hindsight. Even for a young man of 21 he had been spectacularly naive.
He'd always got on very well with Catrina, but assuming that her split with her boyfriend had left the way open for him had been unwarranted: her reply to his declaration of love entirely predictable.

"Switching over to internal power now," said Auerbach.

Burrell sighed.

Catrina had never seen him as anything but a friend. To rub salt in the wounds she'd claimed she'd now become involved with somebody else.

As a second year Engineering student, he should have realised the folly of turning down Auerbach’s offer of a summer placement with the New London Interplanetary Society. He’d done so in order to join Catrina on the hastily assembled archaeological expedition. But his decisions at that time were generally testosterone-led. Come to think of it, would he have accompanied Olwen Rees that night if he hadn't fancied her?

Auerbach continued to intone the final stages of pre-flight liturgy. "T minus thirty seconds and counting. Vehicle is now on internal power. Umbilicals disconnected."

Not long to go now. Burrell’s heart began pound. He drew a deep breath. “Here we go,” he muttered. The countdown entered its final stage.

"- Ten – Nine – Eight - Seven - Six - Engine sequence commence - Five - Four - Three -" Auerbach intoned.

A distant rumble that grew to a thunderous roar.

"- Two - One - Zero. All engines running. Lift-off - we have lift-off."

"The clock is running," Burrell called.

"Lift-off of Pathfinder One at thirty-two minutes past the hour --"

"Spacecraft systems all go," Burrell reported.

He felt a terrible jarring motion, throwing him from side to side.

"Tower clear!" Auerbach announced.

The spacecraft rose in a fury of sound. Now Burrell felt a mounting pressure on his chest. Forty seconds after lift-off, the shuddering began to smooth out as Pathfinder One broke through the sound barrier. But the weight on his chest climbed remorselessly. His arms and legs felt like lead. The accelerometer read three gravities and continued to creep upwards.

"Lift-off AOK," Auerbach said reassuringly. "Pathfinder One, you're looking good."

Lycurgus and Olwen picked their way across the moonlit ruin of what had until a few days ago been a prosperous vineyard. The heavy smell of sulphur hung in the air.
Ahead of them the ground was riven as if by a gigantic meat-cleaver.

"That must be the fissure," Olwen said, excitement evident in her voice.

Olwen shone her torch down into the blackness. The fissure seemed to slope down reasonably gently.

"How deep is it?" Lycurgus cast an anxious glance at Mount Erebus. An ominous red glow could be seen at the summit.

"According to Potter, about 75 feet. The fissure is two miles long, 30 feet across at the widest point."

They started down, picking their way cautiously over the uneven ground.

"Do you think these remains really could be a thousand years older than Novacastra?" Lycurgus asked.

"Potter thinks so, based on geological evidence. Of course he couldn't comment from an archaeological perspective."

Olwen broke off as a rumble sounded from above. The ground trembled slightly.

"Uh-oh," Lycurgus said nervously.

Olwen was unperturbed. "According to Potter, it's been like this ever since the initial quake - the one that opened this fissure. It's when Erebus starts ejecting molten material that we need to worry."

"I hope he's right."

Lycurgus made no further comment as they continued on downwards, and presently they were at the bottom.

"It's only about another quarter of a mile," Olwen said, picking out the way ahead with her torch and striding confidently on.

Lycurgus followed, looking up at the narrow crack of starlit sky above. Erebus emitted another ominous rumble. As they continued, the fissure gradually widened, then after about five minutes, Olwen's torch picked out an almost buried house front.

"That is it!" she said triumphantly.

Together they stared into what looked like the front reception room of a small house. Traces of carpet were still visible on the floor, together with what might have been the remains of tables and chairs.

"Oh!" Lycurgus exclaimed as the torch beam fell upon a mummified human body.

"She seems to have collapsed and died while attempting to flee the building," Olwen said.

"She?" Lycurgus said doubtfully.

"These are the remains of a woman," Olwen said, a trifle testily. Surely you can see that!"

Lycurgus, whose lack of familiarity with the female form was a source of embarrassment to him - especially now - stammered "She must have been almost six feet tall."

"So? I'm 5ft11 myself."

"Yes, but in the Classical Era I thought even men were only around 5ft6 on average."

"Gus, this woman isn't from the Classical Era," Olwen said, stepping through what had been the front door of the house. "Come on, if Potter's correct you are in for another shock or two."

"Are you sure it's safe?" Lycurgus replied, but he followed Olwen anyway. She shone her torch along the hallway they had entered. Here and there, plaster had crumbled from the walls. "Professor, that's --" he started.

"Breeze-block, yes. And no, they didn't have that in the Classical Era either."

They entered the front room. Olwen knelt down beside the mummified woman and began to examine her left wrist.

"Is that a bracelet she's wearing?" Lycurgus enquired.

Olwen looked up. "No, Gus, it looks as if Potter was right about this too. She's wearing a wrist-watch."

"Dr. Potter told you about this?"

"Yes, hence my need to see it for myself, before it disappears under another 75 feet of pyroclastic flow," Olwen said, rising to her feet.

"It's clearly a hoax!" Lycurgus protested.

"No it's not," Olwen replied. She took off her backpack and brought out a camera and a flash-gun. "Unless you doubt Dr. Potter's integrity. Nobody else but he and his team have been here since the fissure opened up nine days ago."

"But how could there possibly have been a civilisation as advanced as ours five thousand years ago? And even if there were, how come we've found no trace of its elsewhere?"

Olwen began photographing the woman. “What we are seeing here,” she said, peering into the viewfinder of her camera, “is proof of my theory about the real origin of Mankind.”

Pathfinder One soared on upwards through the ever-thinning atmosphere. Eight gravities weighed down upon Burrell. He could hardly breathe, but he didn't care.

The clock showed two minutes, fifteen seconds. Right on cue came a slight diminishing of the weight on his chest followed by a shudder, as the solid fuel boosters cut out and dropped off.

"Twenty seconds to sustainer shut-down," announced Auerbach.

"Almost there," Burrell breathed.

Another shudder as the escape tower was jettisoned, followed a few seconds later by the lifting of the crushing weight from his chest as the sustainer shut down. Now his stomach seemed to be heading for the top of the cabin as the craft went into free-fall, moving purely under its own momentum. There came a dull thud as posigrade rockets separated the capsule from the booster.

Through the capsule's small rectangular window, the skies deepened from blue to indigo, then as the spacecraft exited the last fringes of atmosphere, it turned velvet black, and then the stars came out.

"Pathfinder One exiting the atmosphere now," he reported calmly.

"Confirm you are on course, Pathfinder One. Your time to the Moon is twenty-six minutes, forty seconds and counting," said Auerbach.

Twenty-six minutes! He was going to make it!

“Tell me, Gus, what do you know about the Theory of Evolution?" Olwen said.

Shocked at the reference to one of the most notorious religious controversies in centuries, Lycurgus was silent for a moment.

"It resulted in Octavian Rees being accused of heresy 150 years ago and forced to recant; the last such case before the Tellurian Inquisition was disbanded," he said eventually. "Wait a minute, Octavian Rees --"

"Yes - I am a direct descendant," Olwen said. "But what do you know of the theory itself?"
Feeling decidedly uncomfortable, Lycurgus trawled through his childhood memories of Scripture lessons.

"Only that the theory is wrong," he said.


Quoting reluctantly from Cardinal Cranfield's Creationism, Lycurgus said, "Man clearly hasn't evolved from any other life form on Tellus. Evolutionists point to fossils they claim are antecedent to animals living today as evidence for their theory - but they are unable to explain the complete absence from the so-called fossil record of creatures antecedent to Man. We should not be surprised, as the whole idea is absurd. How could something as complex as Man evolve by pure chance? Man has obviously been created by God."

"It is difficult to believe that unscientific rubbish like Cranfield is still legally required reading in schools across the Tellurian Commonwealth," Olwen said with a flash of anger. "Do you realise that radiometric methods have definitely established that Tellus has existed for at least two billion years, and probably much longer; and that life has certainly existed for hundreds of million years? Why would God wait all that time before creating Man, who has only been here for a few millennia?"

"I don't know," Lycurgus admitted, "but it doesn't alter the fact that Man clearly didn't evolve."

"Man clearly didn't evolve on Tellus,” Olwen said. “Neither, by the way, did any of our domestic animals - cattle, sheep, chickens, horses, cats, dogs, etc. But all other Tellurian life is consistent with the Theory of Evolution. The fossil record can only be explained in terms of gradual changes, occurring over millions of years. Now, Gus, what does that suggest to you?"

"That most animal life evolved first; then Man and the domestic animals were created by God later on?" Lycurgus suggested.

"Or that Man evolved somewhere else, on another planet, and only came to Tellus later - bringing his domestic animals with him."

"Are you saying man originally came to Tellus in a spaceship?" Lycurgus shook his head.

"With all due respect, Professor, that sounds a bit far-fetched to me. Though probably no more so than the idea of carving the Face of Noah on the Moon in Biblical times."

“Why,” Olwen retorted. “As you yourself have pointed out, liquid-fuelled rockets have already attained altitudes of several miles and there is no reason to suppose that manned spaceflight will not become a reality in our lifetimes.”

“But Professor,” Lycurgus said wearily, “there’s a bit of a difference between going to the planets and interstellar travel. The nearest solar system to our own is more than four light years away. And even if it were possible for our forbears to have travelled such a distance, what happened to this advanced civilisation and why have we found no trace of it elsewhere on Tellus?”

"These remains must be part of the original settlement established by the space travellers,” Olwen said, her face animated. “They hadn’t had time to expand beyond Novacastra before the settlement was destroyed by a major eruption. The survivors lapsed into barbarism before slowly climbing back up the long ladder to civilisation."

"Even if so, surely some record would remain, if only as a legend. Or are you going to tell me the story of Noah’s Ark is the clue?"

"Not the Ark,” Olwen said. “Are you aware that there are two versions of the story of Noah? There’s the widely-known version that occurs in the Tellurian Authorised Bible in which Noah builds the Ark, of course, but the story of the carving of the Face actually comes from the older Orthodox Version in which Noah and his family take shelter on Mount Ararat and –-“

Olwen broke off as the loudest rumble yet sounded from Mount Erebus. The ground began trembling, but this time it did not die away.

"Professor, I think perhaps we should get out of here," Lycurgus said.

"I think perhaps you might be right," Olwen replied. Hastily, she packed away her camera.

They ran for it. Above, the night sky was streaked with red-hot ejecta from Mount Erebus. The tremors became worse, the sound a continual roll of thunder broken by the occasional whistling as particularly large bolides passed overhead.

After what seemed like an eternity, but was in fact no more than a few minutes, they were rushing up the slope, and presently they were back at ground level.

Lycurgus paused briefly to get his breath back and look back at Mount Erebus. The whole top of the mountain was glowing red, and smoke and flames were pouring fourth.

"We must keep going," Olwen urged.

They resumed running. The sulphurous smell was overpowering, giving Lycurgus a constant urge to cough. The noise grew ever louder, even though they were running directly away from Erebus as fast as their legs could carry them. Despite being fifteen years older than he was, the long-legged Olwen Rees seemed to be rather fitter, Lycurgus noted ruefully.

Suddenly the skies were lit up, as if the Sun had risen directly behind them.

"Cover, we need cover!" Olwen shouted.

Lycurgus looked frantically round. "That hollow over there."

"It'll have to do."

Three or four feet deep, the rectangular depression might well have been the remains of one of the early excavations of the site, a century earlier. They dropped down into it and threw themselves down on the ground. Lycurgus landed painfully on a rocky outcrop.

There was a scything roar that sounded as if the Gates of Hell themselves had opened - was this a manifestation of God's displeasure? Lycurgus asked himself. A battering blast tore at him. The heat was stifling. He clung desperately to the outcrop as the merciless pummelling continued; but Olwen had nothing to hold on to. Lycurgus saw her hands claw desperately into the ground as she sought a handhold.

Now he felt as if the air was being sucked out of his lungs. Through a rising grey fog, he saw Olwen's grip fail. She was swept away and hurled bodily out of the hollow.

Lycurgus lost consciousness.

He had regained consciousness in hospital. His survival had been little short of a miracle. A rescue helicopter had spotted Olwen and himself and airlifted them to hospital. He had been suffering from shock and gas inhalation but had been otherwise unharmed. Olwen had not been so lucky; the explosion had thrown her nearly hundred yards from the hollow and she had suffered massive internal injuries.

Rescuers had located Dr. Potter and his team, but they were already dead: killed by inhalation of poisonous gases from Erebus.

Three days after the explosion, Olwen Rees died without ever regaining consciousness, leaving Lycurgus Burrell as the only living witness to what had been so briefly revealed at Novacastra. There was no evidence to support his story – Olwen’s camera had been smashed when she had been swept out of the hollow; and Dr. Potter’s had never been found. Nobody had believed him - except for Robert Auerbach.

It had taken twenty-five years to build a spacecraft capable of making the trip, twenty-five frustrating years of shoestring budgets, a sceptical public and a deeply-hostile Church. Even then the trip would have been impossible had he not been able to persuade the now-elderly Auerbach to abandon his plans to land on the Moon and opt instead for a flyby with a spacecraft fired out of the atmosphere on a sub-orbital ballistic trajectory.

Now Pathfinder One and its middle-aged pilot were less than two minutes away from rendezvous with the Moon, a grey potato dominating his view, growing every second. He switched on the targeting grid and the cameras.

The Face of Noah was clearly visible, no longer foreshortened by its proximity to the Moon's hidden side. Only Burrell was having difficulty seeing any resemblance to a human face.
For the first time he felt a pang of doubt.

"Mission Control, it's negative so far. You're going to have to get me closer. I want a trajectory that will get me to within ten miles."

"Pathfinder One, I don't have to remind you that that's extremely dangerous."

"So's being fired into space in a tin can. I'll need the correction burn at close approach minus one minute."

"Lycurgus, you'll have to accept the facts. Professor Rees was wrong - the Face of Noah is clearly a natural feature."

"Robert, I never told you what Olwen Rees said just before the explosion and what I think she was about to tell me - you'd have thought I was completely mad. It's not only the Face. Now get me closer or I'll do it myself."

"Very well."

As Pathfinder One approached the peak of its trajectory, so the whole of the Face was finally revealed to Burrell. Now he could clearly see that it was a perfectly normal crater whose resemblance to a human face was vague at best.

The cabin shuddered as the thrusters fired. The Moon's rate of approach increased. Desperately Burrell scanned for surface installations; for evidence that would support the theory - but there was none. Was the whole thing nonsense - had he flown to the Moon on a fool's errand? And was he going to get himself killed to boot? For it was beginning to look as if Auerbach had miscalculated and the burn had put Pathfinder One on a collision course.
He held his breath as the Moon came barrelling towards him... then he was soaring up above the lunar equator. He'd missed by no more than a couple of miles. The far side of the Moon, unseen from Tellus for thousands of years, came into view.

Then he saw it.

"Mission Control, I can see two identically-sized perfectly circular holes set into a large rectangular block. I think this is the evidence."

"Are you sure?"

"Pretty sure but the cameras will clinch it. I'm nearing peak altitude now - Oh MY GOD!"

"What is it?" Auerbach said anxiously.

Picked out in lights on the Moon's surface, still burning after thousands of years, were the words:
U.S.S. Ararat: 2260 A.D.
Per Ardua ad Astra

"Come in Pathfinder One. Lycurgus are you OK?" Auerbach called insistently.

"I'm fine, Robert. I've seen the conclusive proof. Olwen Rees was right. The clue is in the old Orthodox Version of the Bible and the story of Noah in which God hollowed out Mount Ararat to provide a floating haven for Noah, his family and the animals. But it was Man who hollowed out Ararat, which must have been an asteroid in his original home system."

"Are you saying the Moon is some kind of spaceship?" Auerbach said incredulously.

"Yes! It was fitted with engines - and turned into a gigantic spaceship to carry Mankind to Tellus."

"But what sort of power could move something that size through space?"

"I don't know," Burrell admitted. "But some scientists believe that enormous amounts of energy could be liberated by splitting atoms. Maybe our forbears mastered the technique."
The Moon was receding, and Pathfinder One was beginning its long fall back to Tellus. The voyage through space would have taken generations, maybe even centuries, and employed techniques that Man was only now beginning to rediscover.

"Pathfinder One, we have confirmed your new trajectory and revised point of landfall," Auerbach said. "Recovery crews advised accordingly."

He had to go back to the Moon, this time to land, explore and learn its secrets. With the evidence now at his disposal, the New London Interplanetary Society should have no problems in obtaining funding and even the Church might drop its opposition.

A sense of triumph and purpose filled Burrell as Pathfinder One approached the outer fringes of Tellus's atmosphere, and he braced himself for the rigours of re-entry.

© Christopher Seddon 2002, 2008