Dennis Bray, Department of Physiology, Development and Neuroscience, University of Cambridge
Brain vs. Machine
Over the past 50 years, sci-fi writers and other visionaries have been
predicting the appearance of humanoid robots able to walk, talk, and act
like people. Over the same period of time our knowledge of the brain
and understanding of how it acts has been transformed. So, as the
singularity approaches, it seems reasonable to ask how close are we to
replicating brain tissue in synthetic form? What are the implications
for the future?
If we ask: “How much and to what degree can artificial machines perform
the same (mental or intellectual) functions as human beings?” there is
every reason to be optimistic. The list of what computers can do seems
endless and it is far harder to think what they cannot do. Many
limitations come under the category of ‘everyday activities’ or ‘common
sense’. Understanding speech and maintaining a conversation is still a
problem, as is human level vision. It will be some time before a robot
plays a good game of tennis or cooks a gourmet dinner from scratch. But
given the phenomenal progress to date and the way intelligent machines
just get faster and smarter every year, one would be rash to declare
that any particular function is permanently beyond reach.
But
if we ask: “How closely do the workings (that is, the internal
structure and mechanism) of automata resemble those of the human brain?”
the response is more problematic. Most robots and intelligent machines
are designed with efficiency in mind. They represent the best solution
to a problem based on current engineering practice, which is rarely if
ever the solution discovered by biology. It is true that bio-inspired
computing has produced neural networks, genetic algorithms, cellular
automata, and other algorithms that mimic some natural process. But even
a cursory examination of any of these applications shows that the
resemblance to anything biological is purely superficial.
There
remain explicit attempts to reproduce the brain solely from the
standpoint of circuitry such as the grand challenge declared by the
National Academy of Engineering to ‘reverse engineer the brain’ and
Henry Markham’s Blue Brain project that seeks to build a human brain in
10 years. These ventures have received enthusiastic support from
physicists and engineers but to many biologists they seem overblown and
unrealistic. It seems fatuous to represent a neuronal synapse—a complex,
structure containing many hundred different kinds of protein, each a
chemical prodigy in its own right—with a single line of code. Such a
model could never incorporate the synthesis and turnover of crucial
molecules or the dynamic growth and shrinkage of synaptic structure that
accompany learning. Nor would it include the local synthesis of
synaptic proteins, the modulating effect of microRNAs, the influence of
glial cells, diffusing hormones, oxygen, and blood flow. Most crucially,
no simplistic computer representation could ever to match the anatomy
and physiology of a living brain, which requires years of development
and learning to mature.
In
summary: I agree that intelligent machines could be capable of at least
reproducing human performance in any specified intellectual task within
a decade (the outstanding exception to this statement being sentience
or awareness, which no one has any idea how to install into a machine).
But as to the question of reproducing a functional human brain, I think
we are still in the dark ages. We probably do not even have suitable
tools to replicate biological ‘hardware’, with its multiplicity of forms
and continual dynamic turnover. And we certainly have no idea how to
connect it up correctly. Until we can install something equivalent to
development and learning, then any computer network we build, no matter
how large and fast, will be empty of function—just another electric
doll.
But
perhaps it will not matter. The next fifty years are going to be very
interesting and many take the view that evolutionary progress is
transitioning from humans to machines, whether we like it or not. Seen
from this vantage point, modeling every last detail of our brain’s
performance becomes less important—a side issue in the grand sweep of
things.
Singularity Hypotheses: A Scientific and Philosophical Assessment contains authoritative essays and critical commentaries on central questions relating to accelerating technological progress and the notion of technological singularity, focusing on conjectures about the intelligence explosion, transhumanism, and whole brain emulation
The only way of discovering the limits of the possible is to venture a little way past them into the impossible (Arthur C. Clarke's 2nd law)
Subscribe to:
Post Comments (Atom)
No comments:
Post a Comment