Dr. Yara Haridi

So for example, let's think of your skin.

There's multiple layers in your skin and some parts of them basically get replaced one-to-one or they get cross-linked or get changed in some chemical way that makes them stable.

So they actually preserve as that tissue that has been infused with new chemicals that are stable.

When did things start getting teeth?

Or if I can like extrapolate that even more, it's like when did things start getting mineralized tissues?

Okay.

So we have this process called biomineralization where we, or organisms as a whole, will basically take minerals from the environment and make a skeleton out of them.

And we're not the first to do that.

You know, sponges have skeletons.

They have glass skeletons.

Shelled organisms like mollusks, they have skeletons too.

Those shells count.

Calcium carbonate skeletons.

Arthropods have exoskeletons.

So just taking stuff from the environment and making your own skeleton.

We do that too.

And so we make bone, we make teeth.

Our skeletons are made of calcium phosphate.

But what's interesting, of course, is that these mineralized specimens fossilize really well.

And so we can go back in time and be like, okay, what's the first animal to have