Alysson muotri, a California medical researcher, used chemistry to transform skin cells into neurons. These neurons have multiplied to create organoids globes made up of interconnected brain cells. Organoids can grow to hundreds of thousands of cells and live for many years. They even produce brain waves that are similar to those seen in premature babies. Muotri says that the most amazing thing about them is their ability to build themselves. He wonders if they will ever be conscious.
These unsettling scientific discoveries, which were not known even 10 years ago are a challenge to our beliefs about life and raise questions for philosophers and bioethicists. Carl Zimmer, an American scientist writer, wrote that brain organoids are troubling. We feel in our bones the ability to make sense of life. These neuron clusters prove it is not.
Zimmer offers a subtle and profound meditation on life science, with unforgettable insights into the future and past of biology. Zimmer also reveals the remarkable complexity and diversity of life and the clever attempts scientists have made to understand its origins.
Descartes believed that life could be explained by matter in motion. Animals were simply complicated clockwork mechanisms. Others disagreed and argued that life was defined by a vital force. Charles Darwin's grandfather Erasmus Darwin predicted evolution by suggesting that this force could be passed from one generation to another, changing over time to create new forms. Mary Shelleys Frankenstein (1818) was inspired by this disturbing tale about the nature and origins of life. Victor Frankenstein is the scientist who revives a body that has been glued together. He is obsessed with the question, "Whence?"
Our brains are extremely skilled at recognizing signs of life, recognising complex movements, and trying to interpret them into intentions. There are also some universally accepted hallmarks of human life. These include metabolism (the living alchemy that converts food into energy), information gathering and homeostasis (how an organism maintains its conditions for life), reproduction, evolution, and death.
The nature of Life Kenneth Branagh portrays Victor Frankenstein in the 1994 film adaptation. Photograph: Tristar Pictures/Allstar
What about the things that live at the edge of life and test our limits? Mosses can survive desiccation. After 600 years, a moss that had been frozen and dried in a glacier was able to be revived. Others can do the same. If you pour water over someone who is just dying from dehydration they won't sit up. However, if you put water on a dry-out tardigrade it will become a moving, feeding and reproducing animal in minutes.
A liter of seawater contains more viruses than human beings. Are they still alive? They do evolve as other life forms, as can be seen from the constantly changing Covid-19. However, scientists believe that they aren't alive because they require another creature's cells to reproduce. Zimmer says they are able to cross the line between life and death.
Carol Cleland is a philosopher who worked with Nasas Astrobiology Institute. She tells Zimmer that searching for a definition to life is futile. Definitions are used to organize concepts. She says that life is not something that can be simply linked together. We want to understand what life is.
She argues that scientists should instead be working towards a theory of life. Non-scientists might be surprised to learn that such a theory doesn't exist.
A new theory describes life as a unique way of putting things together. This theory is called assembly theory and it basically calculates how many steps are required to make something. While a simple molecule might only require one step to form from atoms of matter, a living organism requires more. Materials made by living creatures require more than 15 steps because they are extremely complex. This distinction may be important in determining the difference between random chemistry or living things. Life is a state where matter can spontaneously create things using a lot of assembly steps.
Lee Cronin, a chemist and inventor of this theory of living, has created an innovative experiment at Glasgow University to demonstrate assembly theory. He created a robot that can perform thousands of experiments with various chemicals in a petri plate: the raw materials he hopes to create life.
It is called the DropFactory by him. It is programmed with curiosity, and creates droplets in petri dishes. These droplets look lifelike, but they aren't life. They could serve as a test bed for the final product.
Some of the droplets may cause complex reactions that create new compounds that can store information about a person's condition. Cronins dropslets could even be declared alive one day. He says that we are certain to solve the origin-of life problem within the next few years. Then everyone will say: That was easy.
