Paleo Got It Wrong: We’ve Loved Carbs for Over 100,000 Years | SciShow News

Paleo Got It Wrong: We’ve Loved Carbs for Over 100,000 Years | SciShow News


Thanks to Brilliant for sponsoring this whole
week of SciShow! You can learn more at Brilliant.org/SciShow. [ ♪INTRO ] We used to think that carbs were a recent
addition to the human diet. I mean, that’s why the so-called “Paleo
diet” says you shouldn’t eat wheat or potatoes. But perhaps unsurprisingly, the fad diet trend
doesn’t really capture the science of what people used to eat. And just last week, a new study published
in the Journal of Human Evolution further proved that. You see, the researchers found smoking-gun
evidence that says humans have been eating starches for over a hundred thousand years. Up until recently, the general assumption
was that early hominins were top-level carnivores whose diet was mostly meat. It was thought that our species only started
to buck this trend around 10,000 years ago when agriculture became widespread. But more recent studies have cast doubt on
this idea. For one thing, our genes seem to suggest we
were eating starch a long time ago. Take the gene AMY1, for example, which encodes
the protein amylase. That’s an enzyme produced in your saliva
which helps break down starches into simple sugars. Great apes, and older lineages of human like
Neanderthals and Denisovans, have two copies of this gene. But you, my friend, have as many as twenty
copies of it. There is no reason for our species to have
made and kept so many copies of this gene if we weren’t consuming starches. These copies aren’t new, either — an 8,000-year-old
hunter-gatherer was found to have 13 copies of this gene. And that much duplication doesn’t happen
overnight. Analyses suggests they’re hundreds of thousands
of years old, which would mean that adaptation to a starch-rich diet was already happening
long before agriculture took hold. Archaeological studies also lend a bit of
support to this idea. Charred food remains suggest humans cooked
oats, wild peas, and root vegetables some 65,000 years ago, for example. And archaeologists have also found starch
granules in the fossilized teeth of both Neanderthals and modern humans from around 50,000 years
ago. There’s even evidence of people making bread
or something like it 4,000 years before the advent of agriculture. But last week, an international team of archaeologists
announced the oldest find yet: charred remains from plant starches dating as far back as
120,000 years ago. These were found in ancient hearths from the
Klasies River Cave in southern South Africa. It wasn’t just obvious what the charred
bits were, though. The scientists had to examine them closely
with an electron microscope. That’s an instrument that uses electrons
in place of light to look at specimens in a much higher magnification than traditional
light-based microscopes. With it, the researchers were able to identify
burned bits of roots and tubers — vegetable varieties akin to modern yams and potatoes. In other words, starches. This find is the earliest yet showing that
humans were cooking and eating starch long before agriculture was a thing. This helps explain the existing evidence of
ancient starch consumption from our genomes, and it basically closes the book on other
theories. We weren’t simple meat-eaters back in the
Paleolithic. Humans have loved carbs for a very, very long
time. And judging by how I feel about a can of Pringles,
this makes sense. But while one genetic mystery seems to be
solved, on Tuesday, scientists announced that they’ve uncovered a new one. They found a lineage of yeast that has lost
a bunch of genes supposedly required for life. And yet…it’s alive. The yeast in question is a genus called Hanseniaspora,
which is used a lot in winemaking. During the early stages of wine fermentation,
Hanseniaspora will multiply like crazy. And even when winemakers use multiple types
of yeast, varieties of this yeast grow so fast that they can end up being 80% of the
final yeast population. And it’s not just a fast grower — it’s
a fast evolver. When scientists analyzed the genomes of many
types of yeast, they found that a lot of the species in this genus experience rapid genetic
changes in a relatively short amount of time. So scientists at Vanderbilt University and
University of Wisconsin-Madison decided to take a closer look. And they were astonished to find species without
really important genes. You see, from a biological perspective, some
genes are considered more important than others. Like, the genes that code for proteins involved
in cell division, for example. These are really old genes that have changed
very little over time — presumably because changes to them don’t generally work out
so well. So they’re thought to be super important
— even essential for life. And accordingly, they can be found in pretty
much every living thing ever — except, for Hanseniaspora. The researchers identified two varieties of
this yeast which had completely lost dozens of genes, including ones involved in cell
division and DNA repair. One had branched off into a new lineage about
87 million years ago and evolved quickly, while the other branched off about 54 million
years ago and evolved more slowly. And the fast-evolving lineage lost the most. For example, both lineages lost WHIskey 5,
which helps regulate cell size during cell division, and MAG1, which plays a role in
removing damaged DNA bases. But the fast-evolving lineage also lost a
bunch of other genes that keep cells from mutating. During the process of cell division, there
are various checkpoints that make sure the steps toward division have been completed
correctly before things are allowed to proceed. The fast-evolving lineage lost several of
the genes involved in these checkpoints. This simply isn’t supposed to happen. Letting DNA mutate without repair and cells
divide without oversight should lead to fatal changes occurring relatively quickly — but
somehow this lineage has survived. The scientists think that other genes may
be picking up the slack for the genes that were lost. As for why these species would want to mutate
so rapidly, the researchers pointed out many organisms go through periods of rapid mutation
when the world they live in changes. So, it’s possible that a rapidly changing
environment in Hanseniaspora’s past gave the fastest mutators an evolutionary advantage. And that may mean that, when it comes to evolutionary
strategies, losing genes could be as effective for adaptation as making new ones. The researchers hope that studying this fast-evolving
mutant yeast can teach them more about the basic processes that govern life. One thing’s for sure though: many of the
genes we thought were essential aren’t. I guess Ian Malcolm was right: Life, uh, finds
a way. It took some hardcore genomics research to
figure out what these yeasts’ genomes looked like. And if you want to better understand how that
research is done, you might want to check out Brilliant.org. Their course on Computational Biology, for
example, can help demystify genomics research. You’ll learn the science behind genotyping
and ancestry analysis, among other things. And that’s just one of their in-depth interactive
courses — they have dozens covering topics in math, science, engineering, and computer
science. All of them are designed to be hands-on, with
animations and quizzes to help guide your understanding the whole way through. And their iOS app lets you download your courses
to work through later. Plus, the first 200 people to sign up at Brilliant.org/SciShow
will get 20% off the annual Premium subscription. That unlocks all of their daily challenges
in the archives in addition to the actual courses. And you’ll be supporting SciShow while you
learn. So, thanks for that! [ ♪OUTRO ]