11 Gorgeous Illustrations Of Science’s Biggest Mysteries

Why do we have fingerprints? How long can trees live? Why do cats purr? Artists illustrate humanity's most burning scientific questions.

Why do we have fingerprints? Do immortal creatures exist? How do migrating animals navigate?

In a new book called The Where, The Why, And The How, 75 artists set out to illustrate some of the biggest, strangest, most curious scientific mysteries of our time.

Here are 11 of our favorites.

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What Is Earth’s Hum?

WHAT WE KNOW When seismic instruments listen for earthquakes, they also pick up vibrations from storms moving over the planet’s surface and waves crashing along the world’s coastlines. This generates Earth’s constant, distinct seismic hum. WHAT WE DON’T KNOW There remain some mystery sounds, including a rhythmic buzz emanating from the Gulf of Guinea in the Atlantic Ocean, the sources of which have not been identified.

Why Do Humans And Ants Have So Much In Common?

WHAT WE KNOW Ants, like humans, exist in societies–some warlike, some peaceful–where individuals play specific roles. Ants wage war, enslave each other, and even carry out a form of agriculture.
WHAT WE DON’T KNOW Ants and people both owe their success to a high level of social dependency. Somehow, both organisms must have evolved with this growing cooperative advantage, but the details of that evolution remain fuzzy at best.

How Can Cancer Be Such A Biologically Unlikely Event, And Still Be So Common?

WHAT WE KNOW Cancer forms from mutations to DNA, but not just any mutations: The DNA has to mutate in a way that turns off the cell’s ability to detect its own mutations, and in a way that allows the cell to keep functioning. WHAT WE DON’T KNOW Researchers have identified several genes involved in the mutations leading to cancer, but haven’t figured out how to target those genes in a way that stops the cancerous cells from spreading.

What Is The Circadian Clock?

WHAT WE KNOW Somewhere deep in your brain, there’s a master clock ticking away, keeping the regular patterns of daily life on track. WHAT WE DON’T KNOW Researchers are trying to find out how that master clock synchronizes with the trillions of cells in your body, each of which keeps time on its own local chemical clock.

Why Do We Have Fingerprints?

WHAT WE KNOW The grooves on our fingers help us grip wet surfaces and sense texture. WHAT WE DON’T KNOW Fingerprints do not–as scientists long assumed–help us grip dry objects.

Do Immortal Creatures Exist?

WHAT WE KNOW Scientists have recovered a 250-million-year-old bacterial spore from a salt crystal and found a Caribbean jellyfish that can regenerate its body repeatedly and then revert back to an immature state when it gets old. WHAT WE DON’T KNOW The mechanisms that allow some organisms to exist indefinitely in a dormant state (like the bacterial spore), or to reverse its age, remain a mystery.

How Do Migrating Animals Find Their Way Back Home?

WHAT WE KNOW Some turtles follow tiny traces of soil carried by ocean currents from distant islands. Other turtles, and some birds, appear to have slightly magnetic compounds that allow them to navigate using Earth’s magnetic field. WHAT WE DON’T KNOW Scientists don’t know exactly how birds use the magnetic field to navigate.

What Triggers Reversals Of Earth’s Polarity?

WHAT WE KNOW The motion of liquid iron in Earth’s outer core generates a magnetic field that protects us from space’s high-energy particles. Every few hundred thousand years, the poles reverse–what was north becomes south, and vice versa. WHAT WE DON’T KNOW Scientists don’t know exactly how liquid in the outer core is moving, how it generates a magnetic field, or how changes in the motion bring about reversals.

Why Do Cats Purr?

WHAT WE KNOW Cats are the only animals that purr. The purr when they’re experiencing pleasure, and also when they’re in distress or pain. WHAT WE DON’T KNOW Several theories exist for why cats purr. They could be purring for social reasons–to get the attention of humans, maybe, or to forge bonds with their offspring or mother. Some research suggests that purring has restorative properties.

How Long Can Trees Live?

WHAT WE KNOW Researchers have dated some bristlecone pines in California’s White Mountains to an age of more than 4,800 years. WHAT WE DON’T KNOW Aspen trees make clones of themselves to build colonies. One such colony, named “Pando,” is estimated to be upward of 80,000 years. Some researchers think that clonal colonies could perpetuate forever under the right conditions.

Can Evolution Outpace Climate Change?

WHAT WE KNOW Evidence from the geologic record suggests that climate change has contributed to several mass-extinction events in Earth’s past. WHAT WE DON’T KNOW The climate is changing faster than most species evolve, but no one knows for sure how much more warming there will be. Under the worst-case scenario, the planet could lose as much as 60 percent of its species in the next century.