How Earth’s minerals set us apart — and could lead us to alien life

One of the greatest unanswered questions in science is, are we alone

Is this a lonely universe in which we're the only living world

or is the cosmos teeming with life with lots of civilizations asking that exact same question

I think if we're going to find an answer, it may very well lie in the realm of minerals

because minerals tell stories. When we look at Earth's early minerals, we see a dramatic change

Before life, there were maybe 1,000, maybe 2,000 mineral species. We have over 6,000 identified today because when life came along

It changed the early Earth's environment. It put oxygen into the atmosphere

It had other chemical processes of metabolism that produce new minerals. And those minerals then become a very sure sign of life and the co-evolution of the geosphere and the biosphere

So how is it possible for minerals to provide clues about life, especially life on other worlds

In some cases, it would be obvious if we found a nice big shell or a bone or a tooth made out of minerals

that's a pretty clear sign. And there's other kinds of fossils as well that might point to the living world

And minerals would have to be involved in those discoveries. But there are other more subtle signs There certain chemical signs There certain physical signs And these are called biosignatures And much of the effort in looking at Mars and other worlds in our solar system

is to seek out those biosignatures. For example, there's lots of different ways to form

pyrite. But the biological pyrites are always very, very fine-grained. Nanoscale, the microbes that

precipitate the pyrite, make a different kind of pyrite. And so we look for the mineral species

that can form biologically in ways that are different from the ways they form if there's no life

around. And sometimes it's just the sweet of minerals. There's certain combinations of minerals

that could only form if you had a living world, for example, certain bright blue and green copper

minerals or purple cobalt minerals that are just beautiful, but they're clues for life as well

And maybe it's even more subtle. Maybe it has to do with the whole diversity of the mineral kingdom that you see

The moon only has about 300 minerals. Mars, maybe 400, maybe 450, we haven't quite figured that out yet

Earth, 6,000. That's a sign of life. And so minerals in many different ways, some obvious, some subtle, point to a biosphere

And with the trillions of trillions of trillions of planets out there, it's inconceivable that we're alone

If nature does something once, it's likely to do it all the time