Tag: paleontology

The Human Family Tree

Our planet was very different 100 ka ago, and if we could survey that time, we would be astounded by the human diversity across its surface. To enumerate what little we know with certainty, there were at a minimum: modern humans, Neanderthals, at least 3-4 varieties of Denisovans, and 2 pygmy Homo populations in Southeast Asia. Likely there were still remnant Homo erectus in Southeast Asia as well, and other diverged lineages within Africa, and a new Homo in Nesher Ramla, Israel, in the Middle East with affinities to Neanderthals.


2023-02-04: More evidence of a much more distributed situation

“Cognitive revolutions”—such as the widespread shift some 300 ka BP from clunky, handheld stone tools to more refined blades and projectile points—were probably instances of different populations with distinctive cultural and biological features coming together and recombining their genes and ideas.

This mosaic evolution would explain certain seemingly unexplainable findings. For example, researchers found human fossils in the Democratic Republic of Congo that dated to 22 ka BP but physically resembled people living 300 ka BP. In Senegal, scientists uncovered 12 ka BP stone toolkits that could easily be transplanted to a situation 100 ka BP.

These finds probably resulted from periods of isolation where different populations in different parts of the continent each developed distinctive cultural and physical adaptations to their local environments. At the same time, instances of connectivity allowed different populations to acquire beneficial traits, behaviors, and technologies from one another, becoming better adapted and more flexible.

Homo Nesher

The bones of an early human, unknown to science, who lived in the Levant at least until 130 ka ago, were discovered in excavations near the city of Ramla. Recognizing similarity to other archaic Homo specimens from 400 ka ago, found in Israel and Eurasia, the researchers reached the conclusion that the Nesher Ramla fossils represent a unique Middle Pleistocene population, now identified for the first time.

320 ka behavior leap

10s of collaborators at institutions worldwide worked to analyze the environmental record they had obtained, which is now the most precisely dated African environmental record of the past 1 ma. early humans at Olorgesailie relied on the same tools, stone handaxes, for 700 ka. Their way of life during this period was remarkably stable, with no major changes in their behaviors and strategies for survival. Then, beginning around 320 ka ago, people living there entered the Middle Stone Age, crafting smaller, more sophisticated weapons, including projectiles. At the same time, they began to trade resources with distant groups and to use coloring materials, suggesting symbolic communication.

Deccan traps

Hull went on to lead a global collaboration that published a definitive timeline of how the mayhem played out in small ocean fossils. The team tracked changes in global temperature over time. The planet did warm up before the impact, but then cooled back down before the asteroid arrived. And while that warming event didn’t seem to correlate to marine extinctions, over 90% of plankton species abruptly vanished after the impact. The study suggests that the major influence of the Deccan Traps was to guide the post-apocalyptic evolution of surviving species — not to drive the extinction itself.

What killed the Dinosaurs?

The greatest area of consensus between the volcanists and the impacters seems to be on what insults to sling. Both sides accuse the other of ignoring data. Each side dismisses the other as unscientific: “It’s not science. It sometimes seems to border on religious fervor, basically”. Both sides contend that the other is so stubborn, the debate will be resolved only when the opposition croaks. “You don’t convince the old people about a new idea. You wait for them to die,” jokes Courtillot, the volcanism advocate, paraphrasing Max Planck. Smit agrees: “You just have to let them get extinct.”

Many more hominins

It seems as if, every few weeks now, a new hominin fossil, genetic study, archaeological site, or re-dating of old sites is reported from the vast Asian continent, a continent that still has large swathes of areas yet to be intensively explored. If nothing else, the picture as it appears thus far is much more complicated than the old Out-of-Africa models: there were multiple earlier dispersals from Africa, and much more interbreeding between species than we once thought. The story of ourselves, it turns out, becomes richer the more we know about it.