Carl Zimmer06 November 2021

What Are The Weirdest Types Of Life? - Carl Zimmer - #394

0Frameworks

10Insights

Insights & moments

The myth-busts, hot takes, explainers, and tools worth keeping.

Myth Buster· 1

Myth Buster01:30

Why Scientists Can't Agree on What Life Is

Despite studying life, biologists often avoid defining it because the concept is so broad and complex. Even within science, there's no consensus on a single definition of life, leading to confusion when discussing viruses, extremophiles, or potential alien life.

Scientists in different fields use conflicting definitions of life.
Many biologists focus narrowly on specific organisms and avoid the big philosophical question.
NASA's working definition — 'a chemically self-sustained system capable of Darwinian evolution' — is one of the most cited but not universally accepted.
The lack of agreement becomes problematic when discussing edge cases like viruses or synthetic biology.

“Imagine like in chemistry people didn't agree on what an atom is — that would be kind of problematic, and yet we're in this situation…”
Carl Zimmer · 01:50

#life-definition#biology#philosophy-of-science#nasa

Hot Take· 1

Hot Take50:30

Stop Trying to Define Life, Says Philosopher

Philosopher Carol Cleland argues that defining life is a waste of time — what we need is a theory of life, not more definitions. History shows that understanding came not from defining water, but from discovering its molecular structure.

Definitions based on characteristics (like 'wet' or 'transparent') fail, as with alchemists defining water.
We lack a unifying theory of life, like chemistry provides for matter.
Arguing over definitions distracts from building that deeper understanding.
True insight will come from theory, not semantics.

“Don't try to define life — definitions are pointless. You're wasting your time.”
Carl Zimmer · 50:45

#philosophy-of-science#life-theory#definitions#carol-cleland

Explainer· 3

Explainer05:30

Animals Can Recognize Life and Death Too

Humans aren't the only species aware of life and death. Many animals distinguish living from non-living things through behaviors like avoiding dead bodies or recognizing biological motion, which helps them survive predators and disease.

Fish avoid dead organisms nearby, suggesting recognition of death.
Animals detect 'biological motion' — the unique movement patterns of living beings.
This ability has evolutionary benefits: avoiding disease, escaping predators, and responding appropriately to threats.
Our own sense of being alive may stem from similar ancient biological monitoring systems.

“Other species can recognize things that are alive and are not alive... that doesn't mean they have a deep conceptual understanding — but neither do…”
Carl Zimmer · 05:45

#animal-behavior#evolution#consciousness#death-awareness

Explainer10:30

NASA's Working Definition of Life

To guide the search for extraterrestrial life, NASA scientists defined life as 'a chemically self-sustained system capable of Darwinian evolution.' This broad definition helps include potential alien life forms that don’t resemble Earth organisms.

The definition emerged from a 1990s NASA workshop on astrobiology.
It focuses on evolution and chemical self-sustainability, not specific molecules like DNA or ATP.
It excludes viruses for not being self-sustaining outside a host.
It’s widely used but not universally accepted among scientists.

“Life is a chemically self-sustained system capable of Darwinian evolution.”
Carl Zimmer · 11:15

#astrobiology#life-definition#nasa#evolution

Explainer21:00

How Snakes Radically Rewire Their Bodies After Eating

Pythons and boas undergo astonishing metabolic transformations after eating — their hearts, intestines, and livers rapidly grow in size to digest prey, then shrink back. This ability offers insights into human organ regeneration and metabolic disease.

After swallowing prey, a python’s organs increase in mass by up to 50% within hours.
The heart, liver, and intestines double in thickness to handle digestion.
Metabolic rate reaches levels comparable to a galloping horse — sustained for days.
Organs return to normal size once digestion is complete.

“Their metabolic rate is roughly on par with that of a galloping horse — and they keep it up for several days while just lying…”
Carl Zimmer · 25:15

#metabolism#snakes#organ-regeneration#digestion

Story· 3

Story07:30

People Who Believe They Are Dead: Cotard Syndrome

Cotard syndrome is a rare psychological condition where patients believe they are dead, often describing how they died and why they continue to function. Some fear washing down the drain during a bath, convinced their body is just an empty shell.

Patients report detailed narratives of their own death, such as drowning or rotting away.
One woman refused to bathe, fearing she'd wash down the drain.
Brain imaging shows damage in areas responsible for bodily self-awareness.
The condition highlights how fragile our sense of being alive really is.

“One woman said she never bathed because she’d just wash away down the drain.”
Carl Zimmer · 09:15

#mental-health#neuroscience#cotard-syndrome#consciousness

Story26:00

Slime Molds Solve Mazes and Math Problems — Without a Brain

Slime molds are single-celled organisms that can solve mazes, optimize networks, and remember past paths — all without a nervous system. Scientists study them to understand the roots of intelligence and decision-making in life.

Slime molds find the shortest path between food sources, solving complex network problems.
They avoid retracing paths by detecting their own chemical trails — a form of memory.
They can 'solve' mazes by growing toward food and retracting from dead ends.
Their behavior suggests intelligence doesn’t require a brain.

“They’re solving a mathematical problem in order to eat — with no brain, just a single cell.”
Carl Zimmer · 27:45

#slime-mold#intelligence#problem-solving#emergent-behavior

Story54:30

The Scientist Who Thought Radium Created Life

In the 1900s, physicist John Butler Burke claimed radium could generate tiny life forms called 'radiobes' in broth. His experiment was debunked as contamination, but he insisted he was right — a cautionary tale of scientific overreach.

Burke dropped radium into sterilized broth and claimed to see microscopic 'radiobes'.
Others showed the results were due to impure water and chemical artifacts.
He published a book and was briefly hailed as a genius, compared to Darwin.
He spent his life defending a discredited idea — a reminder that science includes dead ends.

“He was the talk of the town — people said he was as important as Darwin. A year later, it all collapsed.”
Carl Zimmer · 55:45

#history-of-science#scientific-failure#radium#artificial-life

Q&A· 1

Q&A44:30

Are Viruses Alive? Scientists Can't Agree

Some virologists say viruses are alive because they evolve; others say no because they can't sustain themselves. The debate forces us to question what 'life' really means.

Viruses evolve rapidly — seen in variants like Delta.
They lack metabolism and depend entirely on host cells to replicate.
NASA’s definition excludes them for not being self-sustaining.
Some viruses carry genes for photosynthesis, blurring the line further.

“One morning a virologist told me, 'Of course viruses are not alive.' That afternoon, another said, 'Of course they are.'”
Carl Zimmer · 45:15

#viruses#life-definition#evolution#debate

Tool· 1

Tool17:30

Tardigrades: The Ultimate Survivors in a 'Third State'

Tardigrades, or 'water bears,' can survive decades in a desiccated state by turning their cells into a glass-like structure. They challenge our binary view of life and death by entering cryptobiosis — a 'third state' where metabolism halts but life persists.

Tardigrades survive complete dehydration for decades, possibly over a century.
They produce special proteins that encase vital molecules, protecting them like glass.
They’ve been sent to space and revived upon rehydration.
In cryptobiosis, they show no metabolic activity — blurring the line between life and non-life.

“They're basically turning themselves into a kind of protein glass — nothing's moving, but they're not dead.”
Carl Zimmer · 18:45

#tardigrades#cryptobiosis#extremophiles#survival