I disagree with Johnjoe McFadden’s criticisms of Steve Jones, but genetics are not the only factor in our species’ survival
Originally published by the Guardian 24th January 2007
http://www.guardian.co.uk/profile/simonunderdown
The geneticist Steve Jones has announced that human evolution has stopped. This is based on a genetic view of the evolutionary process and while it is almost certainly true from a gene-centric perspective, it is really only addressing a small part of what it is to be human. While Jones is absolutely right when it comes to the slowing down of the effects of natural selection on the human gene pool, human evolution is not a purely genetic affair and the path of our development as a species cannot possibly be understood without an examination of the role played by cultural adaptations.
The course of human evolution has displayed a complex relationship between biological adaptations (such as bipedalism or brain size) and cultural adaptations (such as tool use) since the development of the first stone tools, around 2.6 million years ago, in East Africa. The appearance of stone tools in the archaeological record was a major cultural adaptation that provided our ancestors with the ability to manipulate their environment – a process that lead to ever more complex behavioural innovations and one that has continued ever since.
Our earliest hominin ancestors were very different in appearance to us – if still extant, they would look to us very “ape-like”. This was the case for approximately five million years until the appearance, two million years ago, of Homo ergaster – the first human and the first to rely heavily on cultural adaptations rather than biological ones. The process of human evolution from two million years ago onwards was one of relatively small-scale biological changes in tandem with massive and far-reaching cultural development. It was the development of cultural adaptations that provided the basis for our evolutionary success and produced the current genetic pattern that Jones describes. The use of cultural adaptations, such as fire and clothing, removed the need for biological adaptation and meant that the basic body plan of the genus Homo has remained relatively unchanged. Although there are of course differences between species such as Homo ergaster, the Neanderthals and Homo sapiens, the factor that unites us all was the role that cultural innovation played in allowing a wide range of habitats to be exploited without the need for biological adaptation. Massive increases in intelligence, a biological process, provided the raw material for a huge range of cultural adaptation and environmental manipulation.
Johnjoe McFadden argues that Jones’s view is incorrect and that the role of genetic engineering means that we will be soon be entering a period of evolutionary dynamism – a result of being able to tweak our genome to, for instance, remove cancer and other genetic diseases – an interesting idea but it overlooks the fact that many of these diseases take hold later in life, after reproduction, and as such could be argued to be relatively selectively neutral. Genes are not the only factor; the environment plays a huge role in our makeup. Simply put, genetic predisposition to heart disease is not the same as heart disease!
Ultimately, genetics is only part of the story of human evolution. While the process of genetic evolution is clearly slowing down and we are no longer subject to the widespread effects of natural selection, cultural evolution continues to play a crucial role in the development of the human species as it has done for nearly 2.6 million years. The pace of cultural adaptation is still moving rapidly and producing a greater range of variation than at any other time in our evolutionary history. We may be heading for a homogenous genetic future but the human evolutionary story tells us that our culture will continue to evolve and flourish as long as humans are around.
thescienceofhumanevolution 