The Thoughts
of
Louise Leakey
In the rush of today's world, and with more than half of us now living in cities, the majority of people are less and less connected with the spectacle of Nature. How many of us stop to think about our place on the planet, and how close we came as a species to going extinct just 75,000 years ago? How many of us appreciate that all our roots are African, as Homo sapiens left the continent only some 75,000 years ago to populate the globe?
The fossil
record presents an opportunity to contemplate how this human story unfolded,
although we will never find the fossils that represent the complete record, as
preservational events are in themselves very rare. With the discovery of Zinjanthropus
at Olduvai Gorge in 1959, my grandmother Mary Leakey pioneered the research in
East Africa, with my grandfather Louis. Many more spectacular fossil finds have
since been made both in Africa and elsewhere, by many researchers driven to
understand our past. These are exciting times, and new and often unexpected
finds are announced quite regularly. Since I presented this TEDTalk in 2008, we
now know of several new species of hominins from different places in Africa, including
additional fossil material from Lake Turkana, helping us to understand our
own genus Homo.
Technology has furnished us with a fascinating
genetic story as well, allowing us to map the migration of early humans in more
intricate detail than ever before. The work of Spencer Wells, a National
Geographic Explorer in Residence, allows us to participate in his study by
providing a cheek swab to discover how we fit in to this incredible journey of
humanity. In addition, genetic research has confirmed that there was gene flow
between Homo sapiens and Neanderthals. Perhaps even more surprising was the
further discovery that we humans also shared genes with a totally different
hominid species, only known from DNA extracted from a finger bone found in a
cave in Denisova in southern Siberia.
To put the history of life on planet earth into a
time perspective, imagine unrolling a toilet roll down a hillside. If there are
400 sheets of tissue paper in the roll, then the very first life in the oceans
is seen at sheet 240. The age of the dinosaurs begins at sheet 19. Dinosaurs in
their many forms and great diversity are around for 14 and a half sheets.
Dinosaurs are extinct by the end of the Cretaceous, 5 squares from the end,
making way for the mammals. Our story and place on the timeline as upright
walking apes begins only in the last half of the very last sheet. The human story
as Homo sapiens, is represented by less than 2 millimeters of this, some
200,000 years.
Our own individual lifetimes cannot be depicted on
this final sheet of the toilet roll as it would be too thin a line, yet we have
been witness to more change to the planet, to the diversity of life, global
climate and natural habitats in this same time period. We are undoubtedly the
cause of the sixth mass extinction event that the planet has seen in its
history.
The last 50 years has shown an enormous increase in
human population, but also extraordinary leaps in technological innovation. The
question that needs to be asked is if we can rise to the opportunity, to use
our technology to better understand our impact, to stem the tide of extinction
on land and in the oceans, to preserve what we have left, and to discover and
understand more about our past. What the fossil record does do is to force us
to contemplate our place on the planet. We are but one species of several
hominids that inhabited planet earth and like our distant cousins who went
extinct fairly recently, our time on planet earth is also finite. It won't take
much to tip the balance against us.
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