[Marxism] brain science (not PR, Strotsky, or morals)

Les Schaffer schaffer at optonline.net
Wed Jan 11 15:26:46 MST 2006


for comrades wanting to give their brains a rest from debates on Leon,
PR, etc, some studies of the brain and behavior in today's issue of
Nature magazine: one for Charles Brown et al, on teaching, social
knowledge, and brain size, one on brain vs deity (follow-up to ID
debate), and one on "hardwiring" in the brain.

and oh, yea, Nature has an article (not included) covering a discovery
that plants are also contributing to methane release into the atmosphere.

les schaffer


========== teaching, social knowledge, and brain size ==================

Nature 439, 153 (12 January 2006) | doi:10.1038/439153a
Teaching in tandem-running ants

Nigel R. Franks and Tom Richardson

Tapping into the dialogue between leader and follower reveals an
unexpected social skill.

The ant Temnothorax albipennis uses a technique known as tandem running
to lead another ant from the nest to food — with signals between the two
ants controlling both the speed and course of the run. Here we analyse
the results of this communication and show that tandem running is an
example of teaching, to our knowledge the first in a non-human animal,
that involves bidirectional feedback between teacher and pupil. This
behaviour indicates that it could be the value of information, rather
than the constraint of brain size, that has influenced the evolution of
teaching.

An individual is a teacher if it modifies its behaviour in the presence
of a naive observer, at some initial cost to itself, in order to set an
example so that the other individual can learn more quickly. We suggest
that teaching also involves bidirectional feedback between teacher and
pupil. To test whether tandem running fulfils these criteria, we
measured the acceleration of leaders and followers in response to the
stimuli they present to one another.

In our experiments, tandem leaders knew the location of food but tandem
followers were naive (for details, see supplementary information). We
found that the leader only continued the tandem run when frequently
tapped on her legs and abdomen (gaster) by the following ant's antennae
(Fig. 1a, inset; for movie, see supplementary information). The tandem
leader therefore modifies its behaviour in the presence of the follower.

We also found that tandem leading imposes a cost on the leader in that
she can proceed four times faster from the nest to the food when not
encumbered by a follower (median speed was 1.8 mm s-1, compared with 8.4
mm s-1; Mann–Whitney test, P<0.0001). [snip]

We next tested whether the leader provides a demonstration of how to
find food. Followers found food more quickly when tandem running than
when searching alone (mean time was 201 s, compared with 310 s; ANOVA,
d.f.=1, F=6.40, P=0.016), indicating that the follower learns more
quickly as a result of the leader's help. [snip]

Bidirectional feedback between the leader and follower is evident from
their patterns of acceleration and deceleration as a function of the
strength of the stimuli they present to one another (Fig. 1): when the
gap between the leader and follower grows too large, the former
decelerates and the latter accelerates; both move at the same speed when
at the maximal antennal reach of the follower.

Together, our results show that the leader's performance fulfils all the
criteria for teaching, with the follower acting as pupil. The lessons
learned by tandem followers are transferred when they become tandem
leaders8, so — although tandem runs are slow — they propagate
time-saving knowledge among foragers.

[snip]

Bidirectional feedback between teacher and pupil distinguishes teaching
from broadcasting. Most recruitment in large ant societies is
broadcasting (for example, through pheromone trails), which is effective
in big groups. But in small societies, where information is valuable and
easily lost, teaching works better. Our identification of teaching
behaviour in an ant shows that a big brain is not a prerequisite.


===== Brain vs Deity =====
Nature 439, 138 (12 January 2006) | doi:10.1038/439138a
Neuroscience gears up for duel on the issue of brain versus deity

Kenneth S. Kosik

1. Neuroscience Research Institute, Department of Molecular and Cellular
and Developmental Biology, Bio II, University of California, Santa
Barbara, California 93106-5060, USA

Sir:

The argument over evolution versus intelligent design, discussed in your
News story "Day of judgement for intelligent design" (Nature 438, 267;
2005), is a relatively small-stakes theological issue compared with the
potential eruption in neuroscience over the material nature of the mind.

Siding with evolution does not really pose a serious problem for many
deeply religious people, because one can easily accept evolution without
doubting the existence of a non-material being. On the other hand, the
truly radical and still maturing view in the neuroscience community that
the mind is entirely the product of the brain presents the ultimate
challenge to nearly all religions.

The slow ramping up of this debate, from Descartes' dualism in the
seventeenth century to the neurophilosopher materialists' claims of
victory today, is about to spill over from an esoteric mind–brain debate
to the divisive question of whether a product of the mind, such as God,
can have any traditionally valid existence whatsoever.

The debate becomes whether a deity, on one hand, stems from human
imagination or biological drive or, on the other hand, has an authentic
existence that the brain has evolved to perceive.

The reappearance of dualism brings back dusty old memories of long-ago
battles that may now need to be refought. As we saw from the media
ruckus raised by the Dalai Lama's address to November's Society for
Neuroscience meeting in Washington DC (even if this did turn down to a
rather low simmer on site), the potential for impassioned disagreement
exists.

The matter now stands at an intellectual impasse, waiting for an issue
around which polarized views will crystallize. We can expect some heady
days.





========== hardwiring in the brain ==========

Books and Arts

Nature 439, 139 (12 January 2006) | doi:10.1038/439139a
In the grey zone

Erik Parens

Abstract

If behaviour arises from interactions between genes and the environment,
in what sense is it hardwired?

BOOK REVIEWED - Hardwired Behavior: What Neuroscience Reveals about Morality

by Laurence R. Tancredi

Cambridge University Press: 2005. 250 pp. $28.99

We seem beset by an instinct to make binary oppositions: either our
choices are free or they are hardwired; we are shaped by either nurture
or nature; mental processes are important or physical processes are;
morality is a social construct or it is biological in origin. Yet one of
the most remarkable things about animals like us is that we can see
those binary oppositions for what they are. We can understand why these
'either or's are wholly inadequate for understanding the phenomena at hand.

Laurence Tancredi's book Hardwired Behavior powerfully presents science
that shows the gross inadequacy of the binary terms we often use to talk
about the genesis and character of complex human behaviours. He writes:
"Our brain structures are not immutable; they are susceptible to change
for the better and change for the worse." Indeed, much of the research
he discusses rests on this neuroplasticity. He reports on research
showing that talk therapy can produce neuronal changes. His chapter on
gender differences suggests that changing social conceptions of the
roles of women "will inevitably affect the biology of their brains over
time". He reports on research showing that rats deprived of nurture at
birth fail to express a gene that is correlated with their ability to
handle stress. And he refers several times to a fascinating study by
Avshalom Caspi and colleagues (Science 301, 386–389; 2002), which found
that the likelihood of children becoming antisocial as adults is a
function of both their genomes and their experiences. As Tancredi
observes, this finding "emphasizes the interactive nature of genes and
environment, nature and nurture".

Why then did Tancredi call his book Hardwired Behavior? Because he wants
to underscore that those interactions between genes and the environment
result in brains with strong dispositions. He also wants to convey the
excitement surrounding scientific and technological advances that enable
researchers to glimpse the neural correlates of those dispositions.
Moreover, as a lawyer and a psychiatrist, he wants to show that the more
we understand the neurobiology of those dispositions, the less we should
believe that individuals are as free to choose as judges and moralists
may assume.

So, for example, he describes the horrific childhood environment of the
murderer Ricky Green and, invoking the Caspi study, speculates about
Green's genotype. His primary point is that Green's experience altered
the biology of his brain. He wants us to appreciate the "deeply physical
nature" of Green's dispositions as an adult. This point is in a sense
more profound than it may seem. If one believed that human choices
originate in a metaphysical soul, in an entity beyond nature, then it
would come as a great surprise to learn that human choices emerge out of
staggeringly complex interactions within and between biological and
social systems. But if one long ago gave up the idea of a metaphysical
soul, the point about the deeply physical nature of our behaviours seems
less profound and is potentially misleading.

[snip]

But leaving aside rare cases where a single genetic mutation or brain
lesion causes an aberrant behaviour, much less is known about the causal
pathways that lead to complex human behaviours than this "deeply
physical" language seems to suggest. Moreover, when more is known about
these causal pathways, the essential elements will be not just genes and
neurons, but also words, human relationships and social customs.

To the extent that this "deeply physical" language seduces us into
thinking that our behaviour is hardwired — in the sense of being
determined by genes and neurons alone — it is deeply unhelpful. To the
extent that it reminds us that our choices don't arise in the way the
metaphysical model suggests, it is helpful. And to the extent that it is
an expression of the desire to move from condemning bad behaviours to
understanding them, it is deeply generous.

Thinking entails noticing when we have allowed the instinct for binaries
to keep us from the complexity of the phenomena at hand. In much of
Hardwired Behavior, Tancredi helps us get over that instinct, and for
that we should be grateful.





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