I pursued science due to chance, a career with so many other jobs. I was about to become a doctor at London Hospital medical college when I discovered that I was in fact studying a subject called "anthropology."
Archaeology and fossils were studied in the course. My parents were unsure about my decision to stop taking medicine. Behind-the-scenes visits to London's Natural History Museum were included in my course at University College London.
A Neanderthal skull from Gibraltar was shown to me. I thought I had passed away.
There was a lack of research opportunities when I was a graduate. I was fortunate to get a temporary job at the Natural History museum. I was going to quit academia to become a science teacher, but fortune changed my mind. A month after I received my PhD from Bristol University, I embarked on a scientific trip that would change my life and define my career.
The task was straightforward but not usual. I drove my old Morris 1000 from London to Bristol and then across Europe to visit museums in order to compare the fossils of Homo sapiens and Neanderthals.
Neanderthals were thought to be ancestors of modern humans. To determine whether or not we were descended from Neanderthals, I wanted to use new statistical methods to compare the skulls of two different people and see if they were related.
It was a great adventure for a person who hadn't been out of England. I was upset by some of the things that happened. Both Neanderthals and Cro-Magnons were held in a museum in the Czech Republic that was refused entry by me. I was admitted when the border guards thought I was Che. I had a scruffy beard.
On other occasions, my tent was swept away, my car exhaust collapsed, and I lost 13 lbs in weight, because I had to hold on with a coathanger.
The American anthropologist William Howells donated his hard-won analyses on thousands of recent skulls, which I could use to measure the variation in our species.
In 1974, I couldn’t tell who our real ancestors were or where they had lived
Although it had less processing power than a wristwatch, the central computer at Bristol University was a major bonus. Neanderthals were not likely ancestors of Homo sapiens, who appeared in Europe and Asia about 40,000 years ago. I didn't know who our ancestors were or where they lived in 1974.
There was a lack of genetic information that could be obtained from them and a lack of informative fossils. The idea that a detailed analysis of ancient bones can reveal important data was considered impossible in the 70s. The ages of the fossils and sites looked too young for some important sites in Africa. Radiocarbon dating was still in its infancy and could make age estimates more recent than they really were.
The Jebel Irhoud fossil skull was kept in the Musée de l'Homme in Paris and was one of the key examples. After a curator tried to prevent me from seeing it, I was only able to measure it with the help of Yves Coppens. The skull was thought to have belonged to a Neanderthal. As soon as I saw it, I knew it was not a Neanderthal.
It was quite primitive when it was only 40,000 years old. The skull was thought to show that Africa lags behind Europe and Asia in the development of modern humans. Thanks to new excavations and studies, it has been found that the Jebel Irhoud fossil is 300,000 years old, making it a very plausible ancestral form for humans.
It was clear that modern humans have an African origin.
The debate about the origin of our species was opened up by new discoveries in the 1980's. On one side, scientists like me argued for a recent African origin, while a group known as the multiregionalists claimed that Homo sapiens had existed for more than two million years.
The Neanderthals and Homo erectus were included in places like China and Indonesia. Neanderthals and Homo erectus, fossils from China and Java, are the direct ancestors of modern Europeans.
Modern humans were not a special evolutionary event according to this vision. It was the culmination of more than a million years of gradual change. The first humans emerged from Africa almost 2m years ago and slowly evolved into the Inuit, native Australians and all other diverse peoples of our planet.
Peter and I wrote a paper in Science. We argued that the features of today's Chinese and native Australians were probably 50,000 years old, rather than more than 1m, and that there was no evidence of deep continuity from ancient humans like Homo erectus.
New dating gave us a lot of support. Neanderthal fossils were being given ages that were younger than some Homo sapiens remains found in Israel.
The paper produced by Rebecca Cann and colleagues at the University of California, Berkeley put human origins on the front pages of newspapers around the world. They were able to build up their genetic sequence by taking samples from about 150 placentas. A single female descendant who became known as "mitochondrial Eve" was the result of a sequence of female ancestors being passed on from mother to daughter.
New analyses implied that ‘mitochondrial Eve’ lived in Africa – 200,000 years ago
The analysis implied that the woman lived in Africa about 200,000 years ago.
It didn't use a single fossil and was strong support for an African origin. The inclusion of these genetic results in our papers and conference presentations caused outrage among the multiregionalists and led to a damaging schism in the field of paleoanthropology.
I regret the part I played in the argument. When our ideas are critiqued, we should try to be objective, but scientists are only human and can identify with their theories.
The most important contribution to our understanding of the origin of our species began a decade later, using a specimen from the original skeleton that had been found in the Neander Valley. The work of researchers led by Svante Pbo, who received a prize for his work last year, shows that Neanderthals are from a different line of humans. A draft whole genome of a Neanderthal was created by Pbo and his team.
I had to rethink my ideas about the Neanderthals after reading this work. I had argued that it was not likely that we had any Neanderthal genes. It is possible that interbreeding with them could have happened. Since our paths crossed in Europe and Asia, it would have been very rare and all traces of it would have been lost. We were basically recent African.
I was mistaken. According to the 2010 paper and those that followed, people outside Africa have a small amount of their genes from Neanderthals. About 60,000 years ago a small group of pioneers left the homeland and entered western Asia, but we know that our species had an evolutionary lifespan in Africa of 300,000 years. They met their evolutionary cousins the Neanderthals and interbred.
They carried their genetic material with them as they spread around the world.
We are not completely recent African origin, as I would have said 20 years ago, and some of the Neanderthal genome is still in us today. We did not evolve from Neanderthals but they are part of our ancestors.
Neanderthal interbreeding wasn't the only surprise in 2010 The Denisovans were identified from a whole genome recovered from a finger bone fragment. The ancient people left a mark on us today through interbreeding, and their genetic material can be found in parts of south-eastern Asia, as well as in parts of Australia and New Zealand.
The beautifully preserved fossil cranium from Harbin, which I was recently privileged to study with Chinese colleagues, is believed to be from the Denisovans.
It shows us how much we still have to learn. Most of Africa has not produced a single ancient fossil bone or skull.
The discovery of a small-brained hominin but only 300,000 years old in South Africa shocked the world.
The islands of south-east Asia have produced two huge bombshells this century, the small-bodied and strange H. floresiensis from Flores and the enigmatic Narmada cranium.
We don't know how to fit them into the larger picture. Human ancestry is becoming more complex and exciting and I can't wait to see what the future holds.