Image courtesy Guido4. CC BY-SA 4.0 via Wikimedia Commons
We
don't really know what life is. The best scientists can do is describe
the attributes of living organisms, the most obvious and superficial
being that they seem to have purpose in their actions, they eat or
absorb nutrients from their environment and they reproduce.
Are advanced AI systems or even your phone "alive"?
Robots
of the future will probably be incredibly complex and already some
robots are autonomous meaning they can be given a general task and can
go off and work out how to do that themselves. The Perseverance rover on
Mars is semi-autonomous and has purpose, its task being to search for
evidence of past microbial life. While not reproducing biologically,
future robots may be capable of replicating themselves using raw
materials they source. But does that make them alive? Single celled
organisms like bacteria "feed" by absorbing nutrients through their
outer walls or cell membranes. Bacteria are thought to be living because
they satisfy the criteria for life. However the jury's out for viruses
as they can't do anything useful on their own and simply consist of
virus particles called virions, made from strands of RNA or DNA. To
reproduce, they must infect a host cell, causing the machinery of the
cell to make thousands of copies of the virus which then emerge to
infect more cells. Bacteriophages or simply phages
are types of viruses that infect bacteria and archaea (single celled
organisms without a nucleus). Treatment of diseases with phages that
could destroy infectious bacteria was a practice once used in the early
part of the 20th century but the development of new antibiotics over the
decades meant that phage treatment was sidelined. However the
appearance of antibiotic-resistant bacteria (something predicted by
Alexander Fleming who discovered penicillin in 1928) in the late 20th
century and the slowdown of discovery of new antibiotics prompted the
WHO in 2017 to highlight the need for new approaches to treating
disease.
In this Big Picture Science podcast from the
SETI Institute, the team investigate bacteriophage treatment to combat
the antibiotic crisis.