TV Review: Horizon - What Makes Us Human?

What is it that
separates us from the rest of the apes? This is the question that Professor
Alice Roberts seeks to answer in her programme 'What Makes Us Human?'

The
story starts with a visit to the Max Planck Zoo in Leipzig, home to many of our
closest primate relatives including bonobos, chimpanzees, orangutans and gorillas. We are told of the remarkable
similarities between us apes; the familiar statistic that we share 99 percent
of our DNA with bonobos gets a run-out. We learn about their impressive lateral
thinking abilities - cue shots of chimps using water to raise the level of a
peanut in a tube and working together to
receive mutual gains (bananas).

Perhaps we are not so different then? Not so, Professor
Roberts says; it is us who are experimenting on them, putting them in enclosures
and making TV programmes about them.

The first analysis of
our differences is from Dr Michael Tomasello who explains that rather than
considering humans as the most intelligent species, we should think of
intelligence as having various facets that different species possess. For
example chimpanzees have excellent spatial awareness and quickly grasp causal
relations. However it is the human
culture of learning and sharing knowledge that makes our intelligence so
powerful and contributes to making us unique.

At this point the
programme loses a little focus. Professor
Roberts was pregnant during filming and so there is an overly long introduction
to the next difference: birth and our
offspring. Roberts explains that human babies
are 'a little bit useless' and vulnerable, especially compared to other primate
infants. This has long been explained to biology students (including me) with
the obstetric dilemma concept. The basic idea here is that as a result of
human bipedalism there is a maximum width that a woman's hips can be for
efficient walking. However this limits the size of the birth canal and as a
result a trade-off occurs with the size a baby's head can grow to by birth.

Challenging this idea
is Dr Holly Dunsworth whose research has shown that there is no restriction
on hip widths for efficient walking. Her team have found that the metabolic
rate of a pregnant woman is rather what causes birth to occur 'early'. A baby
is born at the point at which the mother's metabolic rate can go no higher and
so cannot allow for the baby to grow any larger.

The programme then
moves on to look at the complexities of the human brain. Humans have far more
neuronal connections than any other primates. To investigate further, Roberts
visits the geneticist Professor Franck Polleux. There is a rather tedious introduction
to the size of the human genome, before we find out about Professor Polleux's research.
The gene SRGAP2 is particularly involved
in forming neuronal connections and is present in all primates. Humans, though,
have four copies. It is this change that allows human brains to become so
complex, and again, is partially what makes us human.

Measuring this
connectivity requires a huge amount of effort. We meet neuroscientist Professor Jeff
Lichtman of Harvard University. It is his aim to build a 3D map of neuronal
connections by imaging incredibly thin slices of brain and joining them
together using sophisticated computer software. Unfortunately this technology
is in its infancy and so the analysis focuses on statistics of the enormity of
the project.

The programme finishes
with Roberts again returning to her own pregnancy, and the changes that her baby
will go through to become a unique human adult.

Roberts is a fantastic
presenter, and it is clear to see that she is genuinely fascinated by the
topics raised. However there was too much superficial analysis, almost all of
it using ideas that have been knocking around in (or not far from) the public
consciousness for decades. The evidence for the only controversial idea, that
the obstetric dilemma is wrong, was a little unconvincing. Finally, some key features
such as our bipedalism were only briefly referenced or, in the case of human
language, completely overlooked.

With its hour-long running time, this show
could have covered a lot more ground without being overwhelming. Roberts' own pregnancy also features more than
is really necessary. Did we need such a blatant grab for the 'human angle' in a
programme on anthropology?