A little over 30,000 years ago, in  a rainforest in what's now Borneo,   a surgeon knelt over their patient  - a child with an injured left leg.

Using a sharp tool probably made of stone,   they cleanly sliced through the bones  between the child's knee and ankle,   expertly navigating the muscles, veins, and  nerves to avoid death by blood loss or shock.

And the operation was a resounding success.

This is the oldest known surgical operation, and  it took place tens of thousands of years earlier   than many scientists had assumed we’d started  performing such advanced medical procedures.

And it forces us to ask an important  question, one with far-reaching implications… When did practicing medicine  - in all of its varied,   complex forms - become something  that we actually started doing?

While it’s a hard question to answer,  it’s possible that our tendency to heal   one another might have been with us  for even longer than we've been human.

Before the discovery of  that amputation from Borneo,   the next oldest examples of surgery come from  around 7000 years ago, in the Neolithic period.

An ancient farmer in what’s now France had  his left forearm removed, and skulls with   holes drilled in them, in a process called  trepanning, also emerged around this time.

And for a long time, a common view among western  scientists was that the transition to settled   agricultural societies in this period is what  sparked the first major innovations in medicine.

As Neolithic societies got larger and more complex  in their social organization, they developed   sophisticated medical knowledge, skills, and  tools that earlier communities simply didn't have.

But in 2020, when scientists exploring a  cave in Borneo discovered the carefully   buried remains of that ancient amputee,  they argued that this might be wrong… Because the evidence from that  burial pointed to an intentional,   skilled operation, and not an accident.

For example, the bones of the lower third of  the individual’s leg ended in a clean cut.

This cut was far too precise for the limb  to have been severed in an accidental   injury or an animal attack, both of which  would have left more crushing fractures.

There also was no sign of  an infection in the bone,   probably thanks to the application of  medicinal plants native to the region.

And this would have been quite  an achievement in the tropics   where wound infection is difficult to  prevent and hard to treat even today.

In fact, based on the pattern of bone  healing, the individual appears to have   survived for between 6 and 9 years after  the operation, making it to around 20-ish.

Now, the fact that ancient people  were capable of such sophisticated   behavior shouldn't come as too much of a surprise… The more we learn about the  people who came before us,   the clearer it becomes that  ingenuity, resourcefulness,   and compassion are all traits that have been  part of us for as long as we've been human.

But what about medicine?

After all, from an evolutionary perspective,   practicing medicine is a trait, too - a complex  social behavior, and an unusual one at that.

So if it’s older than the Neolithic period,  and older even than the burial from Borneo,   how much farther back can we trace it?

Well, self-medication is actually pretty  widespread, popping up in various,   diverse animal groups across the family tree.

Many species have been observed seeking  out and using particular medicinal plants,   often to treat or ward off parasites, for example.

From bears, to birds, to elephants,  to us primates, self-medication seems   to be a routine and probably fairly  ancient behavior in the animal kingdom.

But the social aspect of medicine  – not just trying to heal yourself,   but actively trying to heal others – is much  harder to identify outside of Homo sapiens.

And even for other extinct human relatives  who we know were like us in so many ways,   it’s not something we can easily determine if  they were doing based on fossil evidence alone.

But we do have evidence that other human relatives   cared for individuals with injuries  and illnesses, helping them to live   with conditions that would have otherwise  left them unable to survive by themselves… Like the male Neandertal from Iraq called Shanidar  1, for example, dating to around 40,000 years ago.

He lived with a range of debilitating conditions   that meant he was likely cared  for by his wider community.

It’s a case that we dug into in our episode  ‘The Neandertals That Taught Us About Humanity’.

And I recommend that you watch it because  Shanidar I - I got much respect for him.

And we’ve also found an older hominin  dating to around 1.7 million years ago   who had survived years despite losing almost all   of his teeth - again suggesting some  level of care from his social group.

And even further back in time, over 2 million  years ago, we’ve found australopithecines -   members of a genus of early hominins - that  lived with skeletal injuries and illnesses.

Seeing as it would’ve been hard for  them to forage for food and water,   stay safe from predators,  and move from place to place,   some researchers have argued that they, too,  benefited from some level of social care.

But these are all potential examples of hominins  helping each other live with medical conditions,   which is not the same as actively  treating those conditions - aka medicine.

Evidence of that has not been as easy to come by.

We haven't yet found any conclusive examples   of other hominins performing  surgical operations, for instance.

And while it’s a safe bet that they were using  medicinal plants and fungi from their environment   to medicate themselves, we don’t have any direct  evidence that they used these remedies on others… For example, we’ve found traces of medicinal   plants preserved in the dental calculus  of a Neandertal with a tooth abscess.

He seems to have been eating  material from a poplar tree,   which is known to produce a natural painkiller.

If we were to find similar signatures  of medicinal plants in the calculus   of an infant or an immobile adult who  probably couldn’t forage for themselves,   that could suggest that  they were treated by others.

But we haven't - at least, not yet.

The fossil record can only  give us so much information,   and complex social behaviors are  notoriously difficult to infer from it.

So does that mean in our evolutionary  journey, healing each other is something   that we can only say for sure is as  old as our species, Homo sapiens?

Well, until very recently, it  seemed like the answer was yes,   but if the answer was yes, I would not be here.

We just didn't have the hard  evidence to the contrary.

But in 2019, that suddenly changed… See, researchers in the rainforest of Gabon  were working on a long-term project to   observe a local chimpanzee community,  when they noticed something…strange.

Over the course of about 15 months,  the researchers saw wounded chimps   repeatedly perform a never-before-seen behavior.

And when I say this is strange, I would  like for you to go like *this* before I   tell you about it because, when I first learned  about this, it made my brain break in half...

The chimps caught a type of  small flying insect from the air,   squeezed it briefly between their lips,   and applied it to their open wounds - rubbing  it around for a bit before throwing it away.

And the researchers saw the chimps do this  19 times with what seemed like the same   kind of insect - although the researchers  were too far away to identify the species.

Now, this alone was a pretty  remarkable observation.

It was another possible instance of  self-medication in non-human animals,   and the first ever recorded that  involved applying insects to a wound.

But what was even more remarkable  was that, in a few instances,   they saw individuals apply the  insects to the wounds of others.

Those instances included a mother applying  the insects to the wound of her son and,   in one case, adult chimps applying insects  to the wounds of another, unrelated adult.

These observations, published in 2022,  may represent the first recorded example   of non-human animals actively  treating the wounds of others.

And it gives me a little  bit of hope, for all of us.

What medicinal effects the insects  might have had is still an open question.

Perhaps they have some soothing,  anti-inflammatory, or anti-microbial properties.

Until we identify the species, we just don’t know.

But insects and other invertebrates have been  used by many human societies for medicinal   purposes over the years too, from leeches, to  slugs and snails, to termites, to name a few.

And what the chimps are  doing seems pretty similar.

While trying to find deep-time evidence  of healing others has eluded us so far,   it seems like the present may be the key that  helps us understand the evolution of medicine.

After all, if chimps are medicating  each other, isn’t it possible that   this behavior was present in our common  ancestor, some 6 to 7 million years ago?

Whatever the answer, this trait that was  once thought to be exclusively ‘human’   might actually be more widespread than we thought… And maybe even an important part  of our evolutionary success story,   allowing us to thrive in situations that might   have otherwise been deadly – something it  still does for us millions of years later.