HEB Special Hybrid Seminar: Kevin Uno

Mark your calendars - HEB's Dr. Kevin Uno will be giving a Special Hybrid Seminar next Thursday! We look forward to seeing you all there.

Talk Details:

Date: November 5, 2026

Time: 3:15 - 4:15 pm

Location: Haller Hall

Snacks: Provided!

Title: Did the early Miocene rise of grassy woodlands set ape and human evolution in motion?

Abstract: When and why did our ancestors begin walking upright? The “Savanna Hypothesis” posits expanding grasslands selected for bipedalism, but testing it requires reconstructing African landscapes long before the first hominins, 6 to 7 million years ago. Prior to 10 million years ago, this was out of reach: carbon isotopes, the standard tool, cannot tell trees from grasses when both use the same type of photosynthesis. I present a new method that reads plant wax molecules in ocean sediments and ancient soils, where trees and grasses leave distinct signatures, to reconstruct 25 million years of vegetation.

The result overturns the textbook picture of a Pan-African rainforest. Eastern Africa was dominated by dense woodland until 17 million years ago, when a climate shift opened the landscape into grassy woodland, a change invisible to earlier methods. This coincides with apes evolving tougher diets, more terrestrial lifestyles, and their first dispersal out of Africa. These grassy woodlands persisted for roughly ten million years. Partway through, a new type of grass (C4) appeared, at first replacing other grasses, not trees. Only after 7 million years ago did grasslands expand beyond anything seen before, coinciding with the earliest hominins. I suggest that the shift 17 million years ago set the stage for life on the ground, and the later opening favored walking upright between resource (food) patches.