160 for Space Migration

From: Spudboy100@aol.com
Date: Fri Feb 15 2002 - 14:51:26 MST

-If there is no Singularity within, say, 100 years, no successful recoveries
of the cryonically suspended, no sucessful memory upload to clones, no FTL or
relativistic space travel, then this article does have considerable meaning.
"Magic number" for space pioneers calculated
The "magic number" of people needed to create a viable population for
multi-generational space travel has been calculated by researchers. It is
about the size of a small village - 160. But with some social engineering it
might even be possible to halve this to 80.

Anthropologist John Moore from University of Florida tackled the problem as
part of a combined effort with space scientists to determine how in future
humans might successfully undertake century-long journeys out into space.

In the past, attention has been focused on cryogenics, sperm banks and
military-style modes of operation, says Moore, but "the 'right stuff' for a
journey into space is the family - a million-year-old institution designed to
assist reproduction."

Moore has previously studied small migrating populations of early humans and
has developed simulation software - called Ethnopop - for analysing the
viability of small groups.

Marriage partners

For a space trip of 200 years, perhaps eight to 10 generations, his
calculations suggest a minimum number of 160 people are needed to maintain a
stable population.

This would produce around 10 potential marriage partners per person, he says,
and if this seems a small number, "think about how many people you dated
before you got married".

Room would be at a premium on any spacecraft and reducing the number of
people initially required might be desirable. Moore suggests two strategies.
The first is to begin with young childless couples, echoing the practice of
Polynesian seafaring colonists.

The second is to ask the space crew to postpone reproduction to later in
woman's fertile period, perhaps age 35 to 40, creating longer time gaps
between the generations. This measure results in a stable population of just
80 but the consequences of the increased medical risks of late childbirth
have not yet been considered.

A potential concern is that small populations can suffer a damaging reduction
in genetic diversity due to inbreeding, says Dennis O'Rourke from the
University of Utah. He considered the same 10-generation, 200-year journey as
Moore and looked at both genetic drift and inbreeding.

"The decrease in genetic variation is actually quite small and less than
found in some successful small populations on Earth," he says. "It would not
be a significant factor as long as the space travellers come home or interact
with other humans at the end of the 200 year period."

Gene screening

O'Rourke believes that a more serious concern would be the presence of
potentially damaging genotypes in the initial space pioneers. Genetic
screening might well be needed, he says: "Any harmful recessive
characteristics might lead to increased healthcare loads which would deplete
scarce resources."

A final concern raised at the American Association for the Advancement of
Science's annual meeting in Boston was the possibility of infighting. Small
communities isolated for long periods at research stations in Antarctic and
even families travelling on long car journeys, provide examples of how small
conflicts can quickly escalate.

But Moore points out: "Some small island communities on Earth have lived in
peace and harmony for thousands of years because they have developed ways of
solving conflicts. These are not taken to Antarctica."
Damian Carrington, Boston
16:45 15 February 02

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