The Hunt for Food
Origins of Us - Guts
What took us out of the forests, leaving the other apes behind, to spread
out across the globe was our search for food. It's left its mark in our
mouths and in our behaviour. Food makes us behave in the strangest ways.
It's even driven the way we attract the opposite sex. The ways in which we
find food and digest it have not only left there mark on our bodies, but
underpin our success as a species.
The warm waters off the coast of East Africa are home to an
extraordinary creature. A link to our evolutionary past. This strange
looking animal is known as a tunicate, or sea squirt, amd, believe it or
not, this is a distant relative of mine.
It is quite hard to believe I've got anything at all in common with
this sea squirt (Polycarpa aurata). It doesn't have eyes, it doesn't
have arms and legs. In fact, pretty much all it does have is a gut.
He's got an inhole to the gut there, And an outhole over there. It's
a little U-shaped gut. This simple process of food in, waste out, gives
us the blueprint for the guts that lie at the heart of every animal,
including us.
We humans like to think that we are so special, that we're so
different from every other life form. And yet, there is something that
unites us with every other animal on the planet and that is the search
for food.
And the quest to feed ourselves has driven changes in our bodies. The
need for food hasn't just shaped sea squirts, it's shaped us as well,
from our own guts, to the way we move, the way we behave and even the
way in which we experience the world around us.
But, it's on land here in Africa that our story really begins. Over
millions of years, our ancestors' bodies were shaped by the search for
food as they crawled out onto land. evolving into reptiles, mammals and,
eventually, monkeys. 30 million years ago, there weren't any humans on
the planet, there weren't any apes, but there were monkeys.
You and I have evolved from monkeys which would have looked something
like this - Propliopithecus, an ancient primate ancestor that lived in the
trees on a diet of fruit and leaves.
And their search for food has directly affected the way we see the
world today.
Our ancestors flourished in those forest for millions of years, with
first monkeys, then apes exploiting the abundant foods there. And, maybe
they would have stayed in the trees if it hasn't been for a series of
major climate chnages that brought the search for food out of the
trees and down onto the ground.
From around 3 million years ago, the global climate was fluctuating
and becoming cooler and drier. And we know from studies of ancient
climate, but also by looking st the animals that were around at the
time, that the woodlands were shrinking, whilst grasslands were
expanding. So, this was a really important potential habitat if apes
could manage to adapt and find food here.
And adapt they did. Fossil finds have revealed at least six different
species of upright, walking apes living in Africa around this time.
Exactly how they relate to each other, or to us, no-one can be certain.
All we know comes from a few fragmented fossils of species like
Australopthicus africanus and Paranthropus boisei. But, it's clear their
bodies were shaped by the search for food.
This peculiar looking creature is, believe it or not, part of our
ancestral family tree. He was an upright, walking ape, but only about a
metre tall, and he's got a tiny brain case of less than a litre in
capacity. He's got an extremely wide face with flaring cheek bones and a
big muscle would have passed up here, going right up on the side of the
head to this crest on the top. And that is the temporalis muscle, which
operate the jaw. He's got absolutely massive jaws and teeth, and
although his proper name is Paranthropus boisei, this earned him the
nickname of Nutcracker Man.
From the shape of his face its long been thought that Nutcracker Man
survived on the dry savannah by eating hard, dry foods, like nuts and
seeds. But, whatever they were eating, they eventually died out.
Whereas, it seems our ancestors were eating something very different.
The only trouble is, the evidence i being guarded by a formidable
predator. I'm trying to find some lions. The clue I'm looking for is
hidden deep within their food. There's a magnificent male lying
under the trees. They are such huge animals. and these were the
predators that our ancestors were sharing their environment with. And
the lions have found food. The clue I'm looking dor is hidden within the
meat of the lion's victim. That's because most of the animals that lions
kill and eat are carrying parasites. And, as strange as it sounds, those
parasites can tell us something about our ancestors.
Tapeworm
The meat lions eat is riddled with tapeworm larvae, which grow into huge
tapeworms in the lion's gut up to five metere long, attaching themselves to
their host with barbed hooks and leaching off their food. Genetics studies
have discobered that the lion tapeworm is almost identical to a tapeworm
found in humans.
So, this suggests that at some point, humans were eating exactly the same
animals that lions were eating, big herbivores like antelope in Africa.
For decades, the idea of our ancestors as meat eaters and hunters has
only been a theory, guessed at from fossil remains and stone tools. But this
is proof, not only for eating meat, but eating big game.. Proof that is
living inside our guts today. And by dating it, we're able to guess who this
meat eater was - Homo erectus or sometimes Homo ergaster. Homo erectus had a
body shape almost identical to medern humans, with long legs and a
narrow waist. He was amongst the earlirst apes to deserve the name Homo,
meaning human, and he used tools to burcher meat and, perhaps, even to kill
it, as a hunter.
This idea of man as a hunter has been used to explain all sorts of
changes in intelligence, in bodies and behaviour. One of the most obvious
ways that meat eating is thought to have changed us is in the shape of our
faces.The smaller sharper teeth that have evolved in all our mouths seem
well adapted to shearing through the tough muscles fibres of meat.
But, the research doesn't stop there. Using the latest technology to
analyse the surface of our ancestors teeth at microscopic level. Tooth
enamel is the hardest substance in the entire body, but, incredibly, every
time you eat your food leaves it's mark. The evidence of your diet is etched
onto the surface of your teeth in the form of scratches and pits.
From these scratches we can tell what our ancestors were eating, and
we've made a surprising discovery - Homo erectus was, very much, an
omnivore.. Meat might have shaped our teeth, but our ancestors were eating
much more.
And we don't have to go far from teeth to find out what else was in that
varied diet. Samples and tests show that human saliva contains much more of
the enzyme amylase than chimp saliva. Amylase breaks starch down into
sugars, it suggests we are specifically adapted to eating starchy foods. It
means that at some point in our evolutionary journey starch must have become
really important to us. To find out why, we need to go back to where we came
from.
Hadza Tribespeople
This remote part of East Africa has been home to humans for millennia.
The Hadza are a modern people in Eastern Tanzania, living in a similar
environment and eating similar things to our ancestors.
The Hadza are some of the last nomadic hunter gatherers on Earth, and in
the 21st century their diet still harks back to that of our ancient
ancestors. The Hadza live in mobile camps, moving on every few months, and
they live on what they can find in this arid environment. Meat is prized
above all and the men go out hunting most days. Nyanza is one of the camp's
best hunters and, like most Hadza men usually hunts on his own. A hadza
hunter will focus on big game if he can, but finding anything in this
parched bush land is hard, It tends to be the older men, in their 40s and
50s, who bring back most meat. Experience counts for a lot here.
The Hadza love meat when they can get it, but
it's not a reliable source
of food. Only one in 29 Hadza hynts is successful in terms of the men coming
home with big game. Fruit and berries are not available all year. Luckily,
there is something else that's always there, something they can rely on all
through the year - tubers. These are packed full of energy in the form of
starch. Women bring in about 60% of the calories for the group. When food is
scarce, being able to eat a broad range and flexible diet is an obvious
advantage and it meant that early humans, like Homo erectus, became experts
at survival.
