The Evolution of Human Diet

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The California Academy of Sciences presents a talk by Teresa Steele, assistant professor in the Department of Anthropoplogy at the University of California, Davis. Steele’s research focuses on the emergence of the earliest people who were behaviorally, culturally, and anatomically modern.

I highly recommend investing an hour into watching this video. It’s a great archaeology/anthropology introduction for everyone interested in modern diets. It touches on a lot of the main concepts necessary to understand what the heck is being talked about when referencing the methods used to figure out what was going on during the paleolithic era. The talk is super-approachable for intro purposes, but Teresa Steele is also an actual scientist, so more advanced folks will probably appreciate some of what she discusses.

The Australopithecus afarensis to Agriculture Talk (3.4 million – 10,000 years ago)

One concept that seems obvious, but I’d never consciously considered is the size of animals eaten by humans vs. other primates. It’s easy to look at a timeline of the paleolithic and see that human ancestors ate some meat, but there’s a key distinction. Humans eat animals much larger than themselves, while all other primates eat animals much smaller than themselves. Thus, talking about primates as “meat eaters” is factually true, but it ignores a huge difference between Homo sapiens and other surviving species. Hunting large game necessitates a degree of cooperation that is on an entirely different level than the individuality of hunting small game. Since we know Homo neanderthalensis also hunted in groups, we can start to make some interesting comparisons with the rest of the Homo lineage.

I’d like to add to that one of the things that’s unique about humans among primates is how much meat we consume. A large percentage of our calories come from meat on average – compared to other primates. Amongst primates, chimpanzees eat the most amount of meat. And humans on average eat about 10x the amount of meat as other primates.”

The interesting question professor Steele attempts to address in her research and in this talk is: “When did the differences in human and chimpanzee diets evolve?” The implications of this answer impact us in terms of social organization, evolved behavior, and optimal diets in the modern context. A big factor in determining this is that there is little evidence of hominin plant consumption during the Acheulean (~1.6 m – 100,000 years ago) period of the paleolithic. Admittedly, part of this is because plant evidence doesn’t fossilize as well as bones, but it’s interesting that the plant eating assumption persists on such small amounts of evidence. As usual, this refutes the vegetarian position in terms of evolutionary biology.

Humans specialize in nutrient dense, hard to extract sources, while chimpanzees specialize in ripe fruits and plants that have low nutrient density which are also easily collected.”

The relative difficulty of resource extraction also carries implications for human society versus primates. This impacts the necessity of tool use and social organization to sustain expanding populations. Thomas Malthus’ famous prediction that human population would be restricted by a linear growth in the food supply compared to an exponential growth in population comes to mind. The Malthusian limit suffers from an assumption that humans are stuck in the chimpanzee mode of resource collection. To be fair to Malthus, it’s still possible that there is a limit on production that is simply beyond the date he predicted. Thus, the growth in production and population since his prediction doesn’t completely refute his hypothesis. The questions raised by Malthus remain at the foundations of geopolitical debates to this day.

Looking at this from the perspective of adaptive evolution, we also see foundations for hypotheses to explain the explosive growth in human brain size over the paleolithic. Dealing with the problems of tools and groups certainly placed different pressures on the evolution of humans. In other words, the information in this video underpins everything I write about on evolvify. Watch it. Love it.

Methods of study

  1. Archaeological record (tools, artifacts, bones)
  2. Skeletal morphology (bone mechanics & dental structure)
  3. bone chemistry
  • Human Diet Unique in High Meat Content
  • Australopithecus afarensis Diet
  • Cut-Marked Bones 2.5 Million Years Ago
  • Evidence of Ancient Hominids Eating Aquatic Animals
  • Acheulean Hunting and Scavenging (Homo erectus)
  • Exceptional Preservation Sites with Wood Spears
  • Neandertals in Europe
  • Bone Chemistry Findings
  • Hunting Technology
  • Middle Stone Age in Africa
  • Modern Humans in Europe
  • Plant Use
  • Intensification of Resource Extraction
  • Why Humans Replaced Neandertals
  • Conclusive Evidence of Cut Marks
  • Ratio of Fatty Acids in Diet and Brain Size