In 1973, a fossil hunter discovered the partial
skeleton of a female Homo erectus in the Koobi Fora formation of northern Kenya. The specimen dated to 1.6 million years ago;
today she’s known as KNM-ER 1808. Her skeleton was pretty complete, given its
age, including parts of her skull, limbs, and pelvis. And the anthropologists who studied her remains
quickly noticed that there was something strange about the bones of her legs and arms. The texture of her bones was coarse, with
patchy areas of new bone growth. That coarse layer was evidence that something
had seriously disrupted the normal functioning of her bone cells before she died. This would’ve been very painful, and ultimately,
fatal. But what could have caused this condition? Oddly enough, it looks like it might’ve
been something she ate. The researchers who originally studied the
bones considered several possibilities, and no diagnosis was a perfect fit. But, they eventually settled on one that’s
pretty uncommon these days: an overdose of vitamin A. While Vitamin A is usually good for us, helping
us with color vision and healthy immune systems, in high doses it can cause toxicity and a
painful death. We’re talking peeling skin, gastrointestinal
problems, and an increased risk of seizures, along with bone pain and swelling. And those original researchers thought that
the most likely way that this poor Homo erectus got ahold of that much vitamin A was by eating
the livers of carnivores. Now, like us, our hominin ancestors could
- and did - eat pretty much everything. But the downside of this is that it comes
with serious risks - as that Homo erectus found out. We can track our history of eating just about
anything back through the fossil record and see the impact it’s had on our evolution. And when we do, we see that our adventurous
eating habits allowed us to expand our diets, and enabled us to live almost everywhere. So the fact is, there’s never been just
one paleo diet. But throughout time, part of the secret to
our success as a species has been our early - and sometimes fatal - experimentation with
food. A taste for meat was probably disastrous for
that Homo erectus in Kenya, but it’s been a big deal for our genus as a whole. Our early hominin relatives, like Australopithecus
anamensis and Paranthropus boisei, probably had plant-based diets. Likewise, our closest living relatives, chimpanzees
and gorillas, eat lots of what we consider “low quality” foods - things that aren’t
calorie-dense, like grasses, leaves and unripe fruit. And they only get small amounts of animal
protein from insects and the occasional bit of meat. But we think meat and other “high quality”
foods, like fat and bone marrow, probably became a bigger part of the diet early in
the history of our genus, Homo. But there’s still some debate about who
started eating meat first. The earliest widely-accepted evidence of meat-eating
comes from cut-marked bones found at the site of Gona, Ethiopia from about 2.5 million years
ago. The hominins there - probably members of some
early Homo species - were capable of breaking down animal carcasses. But we don’t know how much meat they ate,
or if they were hunting their own prey or just scavenging. So, sites like Gona show us that hominins
could get meat, but it’s hard to tell how often they ate it. Another site, called Kanjera South in Kenya
is the first to show early members of our genus -- most likely Homo habilis or Homo
erectus - eating meat on a regular basis The site dates back 2 million years, and it
includes bones that have been cut into or broken open with stone tools spanning hundreds
of thousands of years. So our ancestors were clearly eating meat
and marrow pretty often by then. But getting that meat came with serious risks. Aside from the inherent threat of getting
injured during a hunt, there are other dangers - like wasting precious energy. Even today, studies of many modern hunter-gatherer
groups show that hunts often fail - even when they’re using things like projectile weapons. And even if those ancient hominins weren’t
hunting the prey, scavenging it from other predators posed its own problems. They’d have to get to the carcass quickly
enough to steal some meat before it went bad, or, if they were feeling less patient, they’d
have to try to drive the predator off of its kill. And neither option was particularly safe. Okay, so what about fish? Less risky than trying to scare a lion off
a wildebeest carcass, right? Well in 2010, a site from that same Koobi
Fora formation in Kenya showed that, about 1.95 million years ago, the hominins there
were fans of seafood. Among the animal remains found at the site
were fossils of catfish and turtles - nice, safe prey. But there were also fossils of crocodiles
found there. So getting attacked by a croc while foraging
for fish or turtles would’ve been a very real hazard. So, in terms of the calories and nutrients it provided, meat was worth it. But it was definitely risky to get. Which is why our ancestors kept eating plants,
too. And while they seem less dangerous to find
and eat, plants have their own fun, unexpected ways of trying to kill us, or at least make
us really sick. Many plants, including things like unripe
tomatoes, contain toxins that act as chemical defenses against being eaten. But you’d only feel the negative effects
if you ate a LOT of it at once. To avoid this, some animals feed on a lot
of different plants in a day. And one of the hallmarks of our genus, as
we’ve evolved, is eating a more varied diet. For example, one study of carbon isotopes
in the fossils of several early Homo species showed that they sometimes foraged from bigger
plants like leafy bushes and trees, but also ate ground plants like grasses and sedges. Being willing to eat different plants made
us more versatile and helped us avoid getting poisoned by eating too much of the same thing. And by continuing to eat our veggies, we gave
ourselves some backup options, in case we failed at hunting or scavenging. So, many of the plant-based foods we might
snack on today -- like cashews or kidney beans -- came with serious risks in the past if
they were consumed raw. But we managed to survive as a species - somehow. And there’s one more thing that millions
of people all over the world eat today, which our ancestors probably enjoyed, even though
it might’ve been painful to acquire. I’m talking about insects and the products
that some of them make, like honey. Bugs are often overlooked as a potential meal
in the fossil record because they don’t leave behind a lot of obvious evidence. Also, since most anthropologists have historically
come from cultures that don’t eat insects, they weren’t thinking of them as food. And honey is pretty invisible in the fossil
record, too, though we do have evidence of fossil bees’ nests from one hominin site
in South Africa. But we know that our great ape relatives today
eat both insects and honey. And eating bugs has its advantages: they’re
pretty easy and safe to get, and they’re unlikely to give us pathogens the way scavenged
meat could. They’re also a good source of protein, fat,
and micronutrients. And honey is incredibly energy-dense. But how can we tell if our hominin relatives
ate insects? Researchers have analyzed bone tools from
the site known as Swartkrans in South Africa, which dates
back 1.8 million years. And the patterns of wear on those tools suggest
that they may have been used for digging into termite mounds. And we know that termites were there because
animals that eat termites have been found there. And there’s also evidence of termite damage
on animal fossils from the site; yeah apparently, some termites seem to eat bone, maybe for
the nitrogen. But there’s a debate about who made those
bone tools, because we’ve found fossils of both Homo and Paranthropus robustus there. Now, while bugs are pretty easy to catch,
some of them have pretty nasty defenses, like venom, or vicious stingers or powerful bites
- so there was risk for our hominin ancestors, too. Like, honey comes with the obvious downside
of having to deal with bees. Not to mention potentially falling out of
the tall trees where some African bees make their hives, which is a real risk for modern
hunter-gatherers who collect honey today. So, both now and in the past, human diets
have varied all over the world, based on what’s available and what different cultures have
been like. But we’ve always been very willing to take
risks for anything that might be tasty. Even in recent history! For example, a study published in 2020 reported
on a series of sites in Norway that dated from between 6300 and 3800 years ago. It found that the bones of cod fish there
contained huge amounts of naturally occurring toxic metals -- more than 20 times the amount
of cadmium and up to four times as much lead as is considered safe today. The fish was toxic, but people ate it anyway. So, our willingness to eat almost anything
is a hallmark of the human story, going back to our earliest hominin relatives. We’ve ingested nearly everything we could
find, insects, mammals, reptiles, fish, birds, plants, and animal byproducts like honey. And so did hominins like Homo erectus. But it didn’t always work out for us, as
KNM-ER 1808 might’ve found out the hard way So, anthropologically speaking, there’s
no such thing as a single so-called paleodiet. We’ve made the best with whatever’s been
available. But we also know that, on the individual level
at least, being an adventurous eater could be risky business. OK if this episode got you hungry for more
human evolution content, be sure to check out our Human Evolution Learning Playlist. You’ll learn the fundamentals about what
we know, and what we’re still discovering, about the evolution of Homo sapiens. And a big thank you to this month’s Eontologists: Patrick Seifert, Jake Hart, Jon Davison Ng,
Sean Dennis, and Steve! And as always I wanna thank you for joining
me in the Konstantin Haase Studio. Be sure to subscribe at youtube.com/eons for
more adventures in evolution.
My brother and I were talking about how our bodies can function on a lot of different things and how it relates to the seasons.
Maybe we ate mostly keto from late summer til spring, when fruits and vegetables were rare, then switched to anabolic mode to fatten up during spring summer.
Clickbait video title by PBS. Should have just been:
Has nothing to do with the modern "paleo diet" (low-carb diet).
Video does talk about how one 1.6 million year old human skeleton had bone growth problems. Scientists surmised that this might have been from Vitamin A overdose because of eating the livers of certain animals. It's just an educated guess, though.
They need to stick to Anne of Green Gables.