In 2020, scientists made global headlines by creating “xenobots” - tiny
“programmable” living things made of several thousand frog stem cells.
These pioneer xenobots could move around in fluids, and scientists claimed
they could be useful for monitoring radioactivity, pollutants, drugs or
diseases. Early xenobots survived for up to ten days.
A second wave of xenobots, created in early 2021, showed unexpected new
properties. These included self-healing and longer life. They also showed a
capacity to cooperate in swarms, for example by massing into groups.
Last week, the same team of biology, robotics and computer scientists
unveiled a new kind of xenobot. Like previous xenobots, they were created
using artificial intelligence to virtually test billions of prototypes,
sidestepping the lengthy trial-and-error process in the lab. But the latest
xenobots have a crucial difference: this time, they can self-replicate.
Hang on, what? They can self-replicate?!
The new xenobots are a bit like Pac-Man - as they swim around they can
gobble up other frog stem cells and assemble new xenobots just like
themselves. They can sustain this process for several generations.
But they don’t reproduce in a traditional biological sense. Instead, they
fashion the groups of frog cells into the right shape, using their “mouths”.
Ironically, the recently extinct Australian gastric-brooding frog uniquely
gave birth to babies through its mouth.
The latest advance brings scientists a step closer to creating organisms
that can self-replicate indefinitely. Is this as much of a Pandora’s Box as
it sounds?
Conceptually, human-designed self-replication is not new. In 1966, the
influential mathematician John Von Neumann discussed “self-reproducing
automata”.
Famously, Eric Drexler, the US engineer credited with founding the field of
“nanotechnology”, referred to the potential of “grey goo” in his 1986 book
Engines of Creation. He envisaged nanobots that replicated incessantly and
devoured their surroundings, transforming everything into a sludge made of
themselves.
Although Drexler subsequently regretted coining the term, his thought
experiment has frequently been used to warn about the risks of developing
new biological matter.
In 2002, without the help of AI, an artificial polio virus created from
tailor-made DNA sequences became capable of self-replication. Although the
synthetic virus was confined to a lab, it was able to infect and kill mice.
Possibilities and benefits
The researchers who created the new xenobots say their main value is in
demonstrating advances in biology, AI and robotics.
Future robots made from organic materials might be more eco-friendly,
because they could be designed to decompose rather than persist. They might
help address health problems in humans, animals and the environment. They
might contribute to regenerative medicine or cancer therapy.
Xenobots could also inspire art and new perspectives on life. Strangely,
xenobot “offspring” are made in their parents’ image, but are not made of or
from them. As such, they replicate without truly reproducing in the
biological sense.
Perhaps there are alien life forms that assemble their “children” from
objects in the world around them, rather than from their own bodies?
What are the risks?
It might be natural to have instinctive reservations about xenobot research.
One xenobot researcher said there is a “moral imperative” to study these
self-replicating systems, yet the research team also recognises legal and
ethical concerns with their work.
Centuries ago, English philosopher Francis Bacon raised the idea that some
research is too dangerous to do. While we don’t believe that’s the case for
current xenobots, it may be so for future developments.
Any hostile use of xenobots, or the use of AI to design DNA sequences that
would give rise to deliberately dangerous synthetic organisms, is banned by
the United Nations’ Biological Weapons Convention and the 1925 Geneva
Protocol and Chemical Weapons Convention.
However, the use of these creations outside of warfare is less clearly
regulated.
The interdisciplinary nature of these advances, including AI, robotics and
biology, makes them hard to regulate. But it is still important to consider
potentially dangerous uses.
There is a useful precedent here. In 2017, the US national academies of
science and medicine published a joint report on the burgeoning science of
human genome editing.
It outlined conditions under which scientists should be allowed to edit
human genes in ways that allow the changes to be passed on to subsequent
generations. It advised this work should be limited to “compelling purposes
of treating or preventing serious disease or disability”, and even then only
with stringent oversight.
Both the United States and United Kingdom now allow human gene editing under
specific circumstances. But creating new organisms that could perpetuate
themselves was far beyond the scope of these reports.
Looking into the future
Although xenobots are not currently made from human embryos or stem cells,
it is conceivable they could be. Their creation raises similar questions
about creating and modifying ongoing life forms that require regulation.
At present, xenobots do not live long and only replicate for a few
generations. Still, as the researchers say, living matter can behave in
unforeseen ways, and these will not necessarily be benign.
We should also consider potential impacts on the non-human world. Human,
animal and environmental health are intimately linked, and organisms
introduced by humans can wreak inadvertent havoc on ecosystems.
What limits should we place on science to avoid a real-life “grey goo”
scenario? It’s too early to be completely prescriptive. But regulators,
scientists and society should carefully weigh up the risks and rewards.