The World Before Us: How Science is Revealing a New Story of Our Human Origins

Tom Higham gives us a fascinating, absorbing history of our species and our genus. We're the last genus Homo species standing, but 50,000 years ago, we were not alone.

Not so long ago, we thought that 50,000 years ago, there were homo sapiens and homo neanderthalensis, and that Neanderthals died out because Sapiens were smarter and more adaptable, and perhaps more deadly to our cousins than they to us. We met in Europe, and they went extinct.

Then recovery and analysis of ancient DNA advanced dramatically, and we got some major surprises.

Among those discoveries is that Neanderthals were not just our cousins, but our very close cousins. Close enough cousins that they sometimes mated and produced offspring, defying our usual understanding show more of "separate species," and some of those offspring were fertile with other homo sapiens. Enough of them were fertile with other homo sapiens that modern humans who are not from sub-Saharan Africa have on average about 1-2% Neanderthal DNA. Neanderthals died out as a separate species, but some of their genes, and their traits, are still with us.

But that was just the beginning.

In a cave in the Altai Mountains in Siberia, remains were discovered of Neanderthals, modern humans, and, to the astonishment and delight of archaeologists, a previously unknown human species. DNA from the pinky finger of a girl, at least thirteen years old at the time of her death, showed that she was a first-generation hybrid of a Neanderthal mother and a father of the species we now call Denisovan. Other Denisovan remains have been found, but we don't yet know this species as well as we know Neanderthals.

But we do know they also interbred with homo sapiens. Denisovan genes may be why Tibetans are relatively well adapted to life at high altitudes. East Asians and Pacific Islanders may have as much as 4 to 5 percent Denisovan DNA.

These were our close relatives, close enough both genetically and in geographic proximity that we interbred with them, at least sometimes, and produced at least some fertile offspring. They weren't the only other humans still sharing the planet with us 50,000 years ago. We've also found homo florensiensis, the "hobbits" of the island of Flores in Indonesia, and homo luzonensis, another small genus homo species, found on the island of Luzon in the Philippines. Homo erectus, previously thought to have been extinct well before this, may also, based on recent evidence, have survived in the islands of Southeast Asia as late as 50,000 years ago.

But DNA recovery and analysis continues to advance, and there are hints of possible other species of genus homo whom we have not yet recovered any fossils of.

My account of this is superficial and dry; Higham's is exciting, rich with fascinating detail and the human experience of finding this evidence, and highly readable.

Highly recommended.

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Very informative and a great read, even if I was very much out of my depth more than once. I will be following Tom Higham from now on.