Carole Allsop ponders the history of our species and recommends a visit to the new Evolution Gallery at London’s Natural History Museum.
Older than we thought
News broke the other day that the Homo Floresiensis or so-called Hobbit fossils have been re-dated. The fossils of several members of this homo species were only discovered in 2003 on the Indonesian island of Flores which lies north of Western Australia. The fossils originally thought to have been around 16,000 years old have now been dated at around 50,000 years old – or just around the time Homo Sapiens made our way into that region of the world. This seems to be the way of things – when our species moves in, other species disappear, including our fellow hominins. The Neanderthals were in Europe and Asia well over 200,000 years before Homo Sapiens, but disappeared around 40,000 years ago soon after Homo Sapiens’ second wave of migration into the region, but this time to stay. The reasons for the disappearance of other homo species are unknown – it is suggested that competition for resources may be one. Looking at our behaviour today, we might speculate whether some of the more ruthless members of our species were responsible for their demise.
Meet the family
The names of all the different homo species – Homo Floresiensis, Neanderthal, Homo Erectus, Homo Habilis, Homo Naledi, the Denisovans – may leave you befuddled. As for the time zones each group inhabited – was it 60,000, 600,000 or 6 million years ago? To make sense of all this, it’s worth paying a visit to the Natural History Museum’s Evolution Gallery, which opened in December 2015. At its entrance is a display of the family tree that puts both the species and the time spans we’re talking about in some kind of perspective. Across a timescape of 7 million years we can see the skulls of our likely relatives, the Australopithecines – whose fossils range from datings of 1-2 to 4 million years ago– and further back in time, the skulls of the earlier more ape-like but almost certainly bipedal hominins, ardipithecus – around 5-6 million years old – and sahelanthropus – 7 million years old or thereabouts. What is evident looking at the family tree is that different homo species may have inhabited the earth at the same time, and our ancestry is anything but simple. Only DNA could give us a more accurate estimate of how the line of descent unfurled.
What are the characteristics of a homo species?
The features we look for after the split from Pan our chimpanzee cousins 7 million years ago are various. It’s all about gradually smaller teeth, less fierce brow ridges, the signs of bipedalism – as indicated by the hole in the base of the skull through which the spinal cord passes along with the narrowing of the pelvis – with unfortunate side effects for the birth canal – arm length, toes that conform to the body line rather than spreading out like gangling thumbs, and skulls that swell above the brow line to contain the growing brain. Fossils that show any of these signs mark themselves out as homo lineage. But piecing the family together – the names and who is related to who – is worse than bluffing your way through the introductions at a wedding, as cousins, second cousins, siblings and half brothers and sisters overwhelm your short-term memory.
Our earliest relatives
In the field of human evolution studies the majority of fossils have been found in the most recent of history, and finds increase exponentially after the 19th century, all of the most ancient ones having been found in Southern or Eastern Africa. Some of our proposed ancestors such as Lucy – a 3.2 million year-old female found in Ethiopia – have become household names. The evolution gallery features a model of her and some might be surprised just how ape-like she was. Though bipedal the arms are not much shorter and the legs not much longer than a chimpanzee’s, and she was probably living both on the land and in the trees. Other names that have become legendary in the annals of homo fossils are featured in the gallery, a replica of Mrs Ples – a 2 million year old skull from the Transvaal – and bones of another South African, the Taung Child, around 3 million years old. Lucy, Mrs Ples and the Taung Child are all said to be examples of austrolopithecus afarensis. Another legendary find in the annals of human evolution is also reproduced at the gallery – the Laetoli footprints – the 3.6 million year-old footprints of a pair of upright walking creatures, probably austrolopithecus afarensis, preserved in volcanic ash in Tanzania.
Moving on in time, a famous name is the Turkana Boy – the skeleton of a boy aged between 8 and 12 years old who lived around 1.2 million years ago. His skeleton was found in Kenya, almost complete and is said to be an example of Homo Erectus. The young Turkana Boy was no quadrupedal knuckle walker, and had been long out of the trees and walking the land. The gallery features a model of him but the original is in the Kenya National Museum in Nairobi, where there was resistance from evangelical Christians when this prestigious skeleton first went on display. Bishop Boniface Adayo protested, ‘ I did not evolve from Turkana Boy or anything like it…these sorts of silly views are killing our faith.’
Moving out of Africa
The earth has revolved some two million times around the sun since those first groups of creatures, members of Homo Erectus – hominins with heavy brows and prognathic chins, but importantly, walking upright – made their way out from the African land mass, driven perhaps by hunger, landscapes grown dry, fear of other hungry hominins of varying shape and form, or even perhaps, just curious. Intrepid groups like these, roved out across the terrain gradually finding their way via land bridges across the continents. Climates shifted and some disappeared, the only evidence a bone here and there. Many of the fossil bones that have been found show signs of some violent blow to a body part, the chances of an encounter with other hominins was rare but likely to be brutal if not murderous, perhaps rape was part of the encounter too. Homo sapiens first moved out of Africa 100, 000 years ago but is believed to have died out quite swiftly though there may have been some interbreeding with Neanderthals. The second wave, some 60,000 years ago was lethally successful for one species. As the Homo Sapiens wave spread across the continents whatever other homo species there were, they disappeared. And there was more interbreeding before they faded away. Many of today’s non-African humans have some Neanderthal DNA contained within their genome and people of Melanesian heritage have inherited Denisovan DNA too. These are unlikely to have been Romeo and Juliet-like tales of cross-species breeding though.
How to treat our relatives
Today we are curious about our human history. Yet our growing understanding of our forebears begs the question ‘how would we deal with our fellow hominins today’ – had they survived, would they be in laboratories, or on display in zoos, the subjects of homo rights campaigns? How sure can we be that we would have treated our more primitive ancient cousins humanely? Would they have been proposed as perfect subjects for medical experimentation? Being so very closely related, they would offer far more accurate results than today’s vivisection subjects. Our more distant relatives, the gorillas, the orang utans, the chimpanzees and the bonobos survived but who has not had a tug of empathy seeing the despondent gloom written on the face of the gorillas at London Zoo? Homo Sapiens has always found justification for the cruel treatment of other species.
How different from us were our more closely related ancestors, Homo Erectus, the Neanderthals? These questions may flit through your mind as you look at the tools and weapons of our relatives and ancestors exhibited in the Natural History Museum’s new evolution gallery. The story of human evolution is constantly yielding new findings – discovered on the Norfolk coast in 2013, the Happisburgh footprints are also well-documented in a video. These 900,000 year old hominim footprints suggest a Homo Erectus group of varying ages, very likely a family or clan, exploring the area, perhaps hunting fish to eat. In 2015 bones of 2 million year old Homo Naledi were found in South Africa – replicas of these are among the NHM exhibits. A remarkable job has been done to elucidate our bushy family tree, and galvanise interest in fathoming where we fit in, how we got here. It will cause you to ponder whether it was our ruthless streak or our fatal intelligence that meant the disappearance of those that walked the same earth at the same time. Homo Sapiens folklore around the world contains a vast stock of humanoid creatures – yetis, ogres, trolls, goblins and gremlins. The mythology of the people of the island of Flores talks of human-like creatures called the Ebu Gogo that could run fast, ate anything they could find and are said to have been hunted to extinction as recently as the 17th century. Who knows, perhaps more bones of Homo Floresiensis remain to be found?
By Cicero Moraes et alii via Wikimedia Commons
Photo attribution (LUCY)
By Donmatas via Wikimedia Commons
Photo attribution (GORILLA)
By Sam Wanamaker via Wikimedia Commons