Human Evolution: The Future
A Tantalising Question
A Parade of Ancestors
Defining a Biped
Useful Links on Human Evolution
- Timeline of human evolution - Wikipedia, the free encyclopedia
- Human evolution - Wikipedia, the free encyclopedia
- BBC - Science & Nature - The evolution of man
The BBC website, with detailed analysis of our evolution.
Two Awesome Books
More on Human Evolution
Human evolution, like all other species technically began billions of years ago, with the very first life forms dwelling in the boiling primordial soup on an Earth we would barely recognise. But when scientists start talking about the origins of humanity, the story begins around 7 million years before our time. At this stage, there are no humans, no chimps just a common ancestor of both swinging through the trees of a tropical rainforest that covered the entire African continent. We have never found any fossils of this mysterious creature, but scientists have already christened it Pan prior. At around this time, according to genetic evidence, the respective lineages split, going their separate ways.
Climate change probably played an important factor in causing the lineage split, at this time Antarctica was entering the final stages of its transformation into a frozen continent, with the process also occurring in the north, with a giant ice cap gradually engulfing Greenland. The freezing of the poles had an extraordinary effect on the world’s weather; lush, tropical rainforests shrank back, replaced by open savannahs covered by a strange new plant, grass, which in turn resulted in the appearance of many grazing animals familiar to us today, such as cattle, deer and antelopes etc.
It was once thought that early hominids walked, blinking and dazed out of their forest homes into the new savannahs. But recent evidence suggests that the first members of the human family tree remained tied to the forests in some capacity for millions of years after their shrinking. Currently, the oldest member of the human family tree is a creature known as Toumai (meaning ‘hope of life’ in the local Dazaga language of Chad- where it was found). The only evidence of this creature’s existence is a skull and a few teeth dated to around 7 million years, precariously close to the human/chimp split. Indeed some scientists have been bold enough to postulate that Toumai may be Pan prior, our last common ancestor with the chimps, but it’s just speculation. How can scientists deduce Toumai’s relationship to us just from us a skull? The key lies in something called the foramen magnum, a tiny hole where the spinal cord slots in. By looking at the position of this hole on a creature, scientists can determine exactly how the spine attached to the skull, and thus reveal whether the creature is a biped or a quadruped. Our foramen magnum unlike all other mammals is positioned at the base of our skull, revealing that we are indeed bipeds. Toumai’s foramen magnum is positioned more similarly to ours than other apes, making it the first biped and our earliest known hominid ancestor.
As time rolls on, these biped hominids adapt to a more open grassland landscape with clumps of forest clinging on. They diversify and speciate, but essentially they retain a close similarity with their chimp cousins, in terms of appearance, behaviour and mental complexity; the only difference being their method of locomotion.
Two of the most famous of these creatures, now known as australopithecines, are Australopithecus africanus and Australopithecus afarensis. Africanus was first discovered by Raymond Dart in 1925 in South Africa; it was a monumental moment at the time, as it was the first creature discovered that vindicated Darwin’s view that our origins lay in Africa rather than elsewhere. Dart, a charismatic scientist adamantly believed that africanus was a vicious killer that used the jaw bones of carnivores as formidable weapons. He also hinted that africanus may have been a cannibal on account of numerous decapitated hominid skulls discovered in South Africa. However, several decades later, one of Dart’s students Bob Brain revealed the truth behind the skulls. He noticed two distinctive puncture holes on top of the cranium, he found the jaw of a leopard and inserted the lower canines into the holes and found a perfect match. So instead of being vicious killers, africanus was cat food, and judging by the quantity of skulls found, a very popular prey item.
Australopithecus afarensis was made famous in the 1970s by an extraordinary discovery in East Africa by Don Johanson; he nicknamed the fossil ‘Lucy’ after the song ‘Lucy in the Sky with Diamonds’ which was playing on the radio at the time. Her remains were astonishingly complete, and seemed to reveal that by 3.2 million years ago, hominids were definitely walking around on two feet. An even more tantalising find was discovered in 1978 at Laetoli, Tanzania by Mary Leaky. A set of footprints left by a bipedal hominid had been perfectly preserved in ash that was laid down around 3 million years ago. As well as hominid footprints, the ash has also preserved footprints of rhinos, antelopes, elephants, carnivores and even records raindrops that fell at the time the ash was being laid down.
By 2.5 million years ago, australopithecines like Lucy were long gone; the climate had continued to deteriorate. The start of the ice ages was just around the corner, the African environment had continued to dry up. In response, two distinct forms of australopithecine evolved; firstly, the robusts, who come to resemble lumbering, bipedal gorillas, they adapted to eating tough vegetation such as reeds that no other ape can live on. The other form was known as the graciles, and they remained similar to their ancestors, except that their craniums, and more importantly their brains were much larger than before. No one knows for sure why brain size began to increase, was it changes in social structure or sexual selection, or a change in diet? Maybe it was a combination of factors; an interesting theory proposed by Richard Wrangham suggests that one of these gracile apes, Homo habilis, normally given the honour of being the first ‘human’ ape on account of its tool making ability, was using these new tools to pound and tenderise meat scavenged from a carcass to make it easier to chew and digest. It seems trivial, but the less time an ape has to spend chewing, the more time it can spend engaging in other tasks, thus stimulating the brain and growing smarter.
Fast forward 500,000 years and a new kind of hominid has evolved; they are first creatures to look like us, the first that we would call human, if we were to gaze upon them. They represented a monumental intellectual leap forward from the australopithecines, possessing brains 50% larger than their ancestors. Again, mystery surrounds the evolution of these more human like creatures, most scientists speculate that a total adaptation to savannah life was responsible for our body proportions and some of our curious quirks such as nakedness and sweating. These new human creatures were the first hominids to step out of Africa, populating large areas of Asia and Europe. Over hundreds of thousands of years, they evolve and adapt in accordance with their local environment. Due to their intelligence, they are also able to adapt their technology, creating better stone tools, better hunting weapons and utilising the power of fire for protection, cooking and warmth.
200,000 years ago, sees the first appearance of our own species in East Africa, at the time we shared the world with four other human species; the Neanderthals, widely distributed across Europe and Western Asia, Homo erectus, still living in Southeast Asia 2 million years after their ancestors first colonised the region, the recently discovered Denisovans, possibly an eastern cousin of the Neanderthals inhabited parts of Siberia and finally the dwarf species from the island of Flores, Homo floresiensis.
Over the next 170,000 years, our species evolved all of the behavioural faculties that make us what we are today, such as art, religion, advanced culture and trade. These factors helped to us gradually break out of Africa, and colonise the entire planet, in the process all of our human relatives go extinct, probably at our expense. Eventually our unique capacity to learn, innovate and literally change our behaviour, result in extraordinary inventions and discoveries; crucially agriculture, then civilisation. With the arrival of civilisation, humanity was now ‘free’ from the daily grind of survival; culture and technology now blossomed like never before.
So here we are, in the 21st century; 7 million years after the human family tree split from the rest of the apes. What exactly does our future hold? Of course, we can entertain notions of what new and wonderful technologies we’ll invent and what impact they will have on society and culture. We can envisage spaceships gliding through the cosmos at tremendous speeds; we can imagine huge machines terraforming a previously lifeless world into an earth like paradise. But what does the future hold for our evolution?
- Is human evolution finally over? | Science | The Observer
Another article from The Observer that attempts to answer this most puzzling question.
- Evolution stops here: Future Man will look the same, says scientist | Mail Online
An article from the Daily Mail supporting the claim that Human Evolution is over.
Is Human Evolution Dead?
Could it be true, that we humans have become so powerful, that we have successfully halted the processes of evolution that have operated uninterruptedly for over 3 billion years? Some scientists seem to think that this is the case. Their argument stems from the fact evolution mostly occurs in small, isolated populations, such as Darwin’s famous Galapagos finches, who spawned over a dozen species, from a single common ancestor, each one adapted to their unique niche.
Darwin’s outline of natural selection, the main driving force behind evolution is that it occurs when a genetic mutation is passed down through the generations, because it offers some sort of benefit to the organism. Eventually the mutation becomes the norm, and you have a new adaptation.
But when you live in a world where isolation does not exist, where the human population continues to grow exponentially and in a world where travel is as easy as it has ever been; then the possibly of any notable evolutionary changes is highly unlikely. It may well be, that the human racial definitions familiar to us today may become blurred as populations continue to merge. But the fuel that drives natural selection may have been totally extinguished. In 1859, the same year the ‘On the Origin of Species’ was published less than a quarter of British children made it into adulthood, today the figure stands at nearly 100%. It seems that the idea of ‘survival of the fittest’ is no longer applicable due to medical advances that allow the so called weakest members of society to survive and pass on their genes. Indeed, scientists even have a name for this, dysgenics- a process where ‘defective’ genes accumulate in the population of a species.
Ian Malcolm Speaks Sense in Jurassic Park
More on Malaria and Sickle Cells
Really Cool Links
- Human Evolution: Are Humans Still Evolving? - TIME
Despite our stable agrarian society and medical advances that help us live into old age, the effects of natural selection are still at work on the modern human species.
- CarlZimmer.com: Articles
A really good essay from Carl Zimmer examining why human evolution is alive and kicking.
The Final Frontier
Life Finds a Way
I’m a great believer in the simple power of nature; one of my favourite quotations comes from Ian Malcolm in Jurassic Park, when he disputes John Hammond’s claim that the dinosaurs cannot breed, due to them all being female. Malcolm is unfazed by Hammond’s confidence and makes a simple statement ‘life finds a way.’ It seems that there are a few scientists out there who agree with Malcolm. They, and I believe that no matter how powerful we become, we will never shut down a force that has operated for billions of years, not entirely anyway.
Indeed a team from Yale University carrying out studies on human reproduction characteristics, have found that over the last few decades, on average shorter, slightly plumper women with low cholesterol levels are having more children than their peers, they also tend to have low blood pressure, as well as choosing to have their first child earlier in life, and experiencing menopause later in life. This trait in turn is passed on to their offspring, suggesting that Darwinian natural selection is alive and well in Homo sapiens, even those living in the developed world.
In other areas of the world, natural selection is also alive and well in humans. I watched a documentary called ‘Human Planet’ on the BBC that profiled an isolated community living high in the Himalayas who have managed to adapt to the altitude spectacularly over thousands of years. It was quite funny to witness these people breathing comfortably, while the camera crew were forced to don oxygen masks.
It’s often thought that humanity has managed to eliminate all of its natural competitors, and while I admit we no longer live in fear of mammalian predators and other megafauna. We still have competitors and predators, except that they no longer have sharp teeth or claws, instead they tend to be so small that we can’t see them, unless under the scrutiny of a microscope; I’m talking about viruses. One of the deadliest viruses in human history is malaria. This disease, carried by certain species of mosquitoes was probably spread by early farmers who cleared forests to create fields, which allowed the mosquitoes to lay their eggs in pools of water. As the deadly virus spread, natural selection favoured humans with greater immunity against the disease. The defence comes in the form of a variant of a haemoglobin gene that makes it hard for parasites to reproduce in blood cells. While one copy will give you virtual immunity against malaria, two copies will give you sickle cell anaemia, as is usual there is a very fine balance between life and death in nature.
We live in an overcrowded, densely populated world, therefore the risk of a global pandemic with a considerable loss of life increases. I mentioned in my hub on ‘Human Extinction’ that no pandemic could wipe us out entirely. Instead, natural selection will favour those humans who have greater resistance to lethal diseases such as HIV, Sars and Influenza.
If we were ever take the leap and spring forth into space and colonise other planets. The colonisers will become an isolated, self sufficient population of Homo sapiens. It’s very doubtful that any colonisers will seek to return to earth one day because of the vastness of the cosmos, therefore the processes of natural selection may operate on these communities, but any notable changes would be determined by the local environment. It’s worth pointing out that the people of New Guinea and Australia remained isolated for over 30,000 years and yet did not evolve into another species. The same goes for the Native Americans, who remained isolated for 13,000 years and experienced no notable evolution.
More on Designer Babies
- BBC NEWS | Health | Designer baby row over US clinic
A controversial news story about a Los Angeles offering would-be parents the chance to select traits like the eye, skin and hair colour of their offspring.
- Designer Babies: A Right to Choose? | Wired Science | Wired.com
An article examining the pros and cons of designer babies
- Designer baby - Wikipedia, the free encyclopedia
More on Transhumanism
- Humanity+ | Technology & the Future
A website devoted to a group of thinkers who see the future of human evolution tied up in technology.
- Future of Humanity Institute - Future of Humanity Institute
- Nick Bostrom's Home Page
The Director of the Future of Humanity Institute at Oxford University.
Just like with domestic animals, we may decide to take charge of our own evolution, using genetic engineering to promote desirable characteristics while eliminating others. We’ve already heard talk of designer babies, essentially humans stuffed with all the best possible genes, essentially this is a mixture of artificial selection and sexual selection, because parents will attempt to ‘make’ a baby with desirable physical and mental traits. As these children grow up, they will then select mates with all these desirable traits, things like attractiveness, height, muscularity (in men) and energy levels.
Another consideration is our growing relationship with machines. According to Nick Bostrom at the Future of Humanity Institute, the future of human evolution lies with learning to transcend our biological limitations using machines. This process is called ‘Transhumanism’ and could potentially lead to the creation of super soldiers, super athletes and even humans who cheat death through immortality, through having their minds downloaded to a computer. He also envisions evolution occurring just as often as it does naturally, but on a much shorter time scale, due to these new artificial beings being able to reproduce much faster than your old fashioned Homo sapiens. As a naturalist, this hypothetical future fills me with dread and fear; I’d much rather put my faith in the power of the natural world; nature is life, life is nature, therefore life will find a way.