Human Evolution

human evolution

Out of Africa, time and again

There is widespread agreement among scientists based on fossil and geochemical evidence that modern humans evolved in Africa between 200,000 and 100,000 years ago before spreading around the world. But the timing and route of this dispersal, and whether it occurred as a single exodus or in multiple pulses, remain contested. Now, a new study throws its weight behind a multiple-dispersal hypothesis, suggesting a first group of modern humans left Africa as early as 130,000 years ago, followed by a second about 80,000 years later.

27 Sep 2014

Spanish cave reveals possible new Neanderthal ancestor

A trove of thousands of hominin fossils unearthed from a prolific cave in northern Spain is proving a boon for paleoanthropologists studying human evolution and the early ancestors of Neanderthals. The fossils are proving difficult to categorize as a recognized species, however, raising the prospect of a new category of hominin for these Middle Pleistocene specimens.

19 Jun 2014

Fieldwork revises ice-free corridor hypothesis of human migration

The existence of an ice-free corridor through Canada during  the climax of last glaciation, which allowed the first Americans to cross the Bering land bridge from Siberia and move south (about 13,000 years ago), has long been postulated in North American archaeology. Now, research based on the exposure ages of glacial rocks found in the corridor suggests a puzzling conclusion — that the open pathway closed several thousand years prior to 20,000 years ago and didn’t open again until between 13,000 and 12,000 years ago, well after  first Americans were in the Americas.

13 Apr 2014

From boom to bust in Neolithic Europe

As agricultural practices spread from the Fertile Crescent across Europe, gradually expanding west and north starting about 8,500 years ago, they brought increased and localized food production to a continent where nomadic hunter-gatherers had long made their living subject to the whims of climate and the environment. With agriculture, long-term settlements developed, fertility rates rose and, thus, populations grew steadily. Or at least that’s been the conventional wisdom.

20 Mar 2014

Down to Earth With: Naomi Levin

Stable isotope geochemist Naomi Levin, a native New Yorker, says she could easily imagine alternate career paths that would have been more in line with her urban roots. But the hands-on nature of both fieldwork and lab work lured her to geology and anthropology. And after working with a string of prominent geochemists — including Jay Quade, Thure Cerling and John Eiler — as a graduate student and post-doctoral researcher, Levin has quickly moved to the top of her field.

09 Jan 2014

Science denialism: The problem that just won't go away

In lieu of doing a "year in review" issue this year, EARTH asked our staff and some frequent contributors to write a short commentary on something that grabbed their attention in 2013. We gave everyone carte blanche. What follows is a collection of extremely varied, often very personal insights into how the planet impacted each individual. In this commentary, EARTH contributor and cartoonist Callan Bentley discusses his run-ins with science denialism.

20 Nov 2013

Hydrological models locate ancient human migration routes

Archaeologists and geologists have long hypothesized that major river systems flowed north through the Sahara Desert about 100,000 years ago. These rivers would have provided a sort of network of “green corridors” across the Sahara that early humans could have traversed as they migrated out of Africa. Ancient lake records, fossil river systems, and radioisotope data have offered evidence for the existence of flowing water in the region.

01 Nov 2013

Hominin skull discovery fuels debate about early human evolution

Hailed as a find for the ages, a rare skull of a 1.8-million-year-old human relative could provide answers to longstanding questions about the lineage of our species. It also fuels debate over what differentiates one hominin species from another, and could mean that Homo habilis, Homo rudolfensis and other early bipedal hominins may all be members of Homo erectus, rather than distinct species.

17 Oct 2013

Oceanic records paint a more complex picture of human evolution

It has long been hypothesized that human ancestors evolved the ability to walk upright — a feature that appeared about 6 million years ago — in response to African landscapes changing from forests to grasslands. Now, a group of scientists has assembled the most continuous timeline of landscape evolution and grassland development over the last 12 million years near the African Rift Valley in northeastern Africa — and the timeline contradicts conventional hypotheses.

17 Jun 2013

Modern humans arrived in South Asia 25,000 years later than previously thought?

Figuring out when modern humans left Africa and migrated throughout the world is a complicated task. For example, some evidence suggests modern humans may have migrated out of Africa and into Asia as early as 120,000 years ago. Further evidence puts modern humans in India and other parts of South Asia prior to the super-eruption of Mount Toba in Sumatra, which took place 74,000 years ago.

13 Jun 2013