Procreation by mail. In another right to procreate
case, prisoner William Gerber sought to have his wife artificially
inseminated with his own sperm. After being given a life-term
under California’s three-strike law – for discharging
a firearm, making terrorist threats, and using narcotics – Gerber
requested prison authorities to permit him to provide a semen sample
to a laboratory for his wife to inseminate herself. He intended
to collect the sample, and mail it to a medical center sperm bank,
where his wife would go to complete the procedure. The prison
warden refused, alleging that the right to procreate was extinguished,
at least temporarily, by incarceration. The district court
found in the warden’s favor, but on appeal, the Court of
Appeals for the Second Circuit reversed. They held that prisoners
are not deprived of the fundamental right to procreate when serving
jail time. While acknowledging that prisoners do not have
a constitutional right to conjugal visits, nevertheless the court
said, this does not bar them from fathering children during incarceration. Sending
sperm through the mail was a legitimate exercise of their procreative
rights. The decision, however, did not apply to female prisoners. Recognizing
the biological differences between men and women, the court said
that a woman did not have the right to be artificially inseminated
with her husband’s sperm while being held prisoner. A
dissenting justice wrote that, while prisoners do not lose all
fundamental rights when jailed, it was “a far cry from holding
that inmates retain a constitutional right to procreate from prison
via FedEx.” Gerber v. Hickman, 264 F.3d 882
(2nd Cir. 2001).
Conflicts between parents and their offspring. Birds
are sometimes willing to sacrifice their own children to have the
chance to breed again. Reproduction is a costly proposal. Parents
must put a lot of energy into finding a mate, producing gametes,
the reproductive process, itself, and then raising their offspring. When
predation is a threat, should parents place themselves or their
offspring at a greater risk of dying? Parental feeding visits
to the nest can increase the risk of predation to both parent and
offspring by attracting the attention of predators. Birds,
faced with the threat of predation, reduce feeding visits to the
nest, promoting both their own and their offspring’s survival. The
reduction in the number of feeding visits has a trade-off. Too
few visits can increase offspring mortality when the offspring
suffer from the lack of food. Birds who have a smaller clutch
size put more of the predation risk on their offspring, then birds
who have larger clutch sizes. Parents tolerate greater risk
to themselves, but not their young, in species with many offspring
because the offspring in larger clutches are more likely to survive
to a reproductive age. Parents with few offspring, in contrast,
tolerate less risk to themselves because, with the lower numbers
of young, there is less a chance that any one nestling will survive
to reproductive age. Ghalambor and Martin, Science,
292: 494-497, 20 April 2001; Pennisi, Science, 292: 414,
20 April 2001.
The Big-Bang. Some organisms exercise the right
to procreate only once in a lifetime. “Semelparity is the
so-called big-bang reproductive strategy, in which an animal invests
all in a single mating season, dying soon afterwards. This
is not a strategy one immediately associates with mammals. Nonetheless,
semelparity does occur in terrestrial mammals … [M]ale northern
quolls (Dasyurus hallucatus) — relatively large marsupials
that weigh more than a kilogram — all die after their first
mating season. … Females of studied … Dasyuridae
species have a highly synchronized, single oestrus (during which
ovulation occurs) in the winter, and males commit themselves totally
to obtaining mates at this time, at the expense of future mating
attempts.” The evolutionary significance is not understood,
but it has been proposed that “[s]exual selection might be
the driving force: females might be biased towards young, vigorous
males, meaning that there would be little reproductive benefit
to the survival of older males. Alternatively, circumstances might
be such that the intensity of fighting between males during the
rut means that only the youngest and fittest can win and survive
to mate. The cost of such fighting might be reduced lifespan. These
ideas, although speculative, illustrate the need for further studies
to determine which ecological or evolutionary circumstances promote
this extreme, and extraordinary, reproductive tactic in a relatively
large mammal.” Humphries and Stevens, Nature,
410, 758-759, 12 April 2001. Originally described by Oakwood, M.,
Bradley, A. J. & Cockburn, A. Proc. R. Soc. Lond. B,
268, 407-411, 2001.
Does sex matter? Many organisms reproduce themselves
without the benefit of sex. Bacteria, for instance, reproduce
by simply splitting into two by a process called “binary
fission.” Plants can reproduce asexually (“vegetatively”)
by forming new plants from portions of their roots, stems, or leaves. These
vegetatively-produced progeny are clones of the parent plant. Even
more intriguing are organisms which have both male and female parts
that can self-fertilize. Many land snails and slugs are self-reproducers – capable
of producing progeny completely on their own, using self-made sperm
and self-made eggs. Self-reproduction is less costly than
sexual reproduction. Self-reproducers do not have to waste
resources on elaborate courtship behaviors to find a mate. As
a consequence, they have more resources to invest in their progeny,
and, at least theoretically, should surpass sexual reproducers
in the quantity and presumably quality of their offspring. Surprisingly,
self-reproducers have not taken over the world. Although
non-sexual reproduction is observed in almost every family of organisms,
sexual reproduction predominates. There must be something
wrong with self-reproduction that explains why it has not become
the predominant procreative mode, despite its economic efficiency. The
explanation most often proffered is that sexual reproduction is
more advantageous because it generates greater diversity in offspring
by combining the genomes of two unrelated organisms having different
sets of genes. Greater diversity means more variation to
cope with a changing world – disease, parasites, environmental
upheavals, etc. Variation, after all, is the substrate of
natural selection.
Contract and consideration genes. Say A has “sucker” genes
and B has “rip-off” genes. An individual who
has sucker genes is easily cheated and deceived, again and again. He
never learns. Rip-off genes, on the hand, predispose an individual
to exploit others. He always wins. A’s sucker
genes make him less fit for survival because, by losing to B, he
is giving up valuable resources that he needs to survive. Sucker
genes damage his reproductive potential. As a result, the
sucker genes are selected against, and their frequency in the gene
pool diminishes. B, on the other hand, is more robust because
of his rip-off genes.
What happens when a B contracts with another B? Neither
party is willing to give anything up until something is given up
first by the other party. There is deadlock. The effect
on fitness is the same as it was for A in the A and B contest. Neither
B gets anything. Exploitive genes are good only in the short-run
when sucker genes are abundant.
Say C arises who has “consideration” genes which promote
valuable exchanges between parties. Between C and A, resource
allocation will be maximal because each party is willing to exchange
something of value in order to get something of personal value
to them. Cs won’t exchange with Bs unless B is willing
to give something up in return. If Cs win when bargaining
with As and Cs, but win only with As, in the long-run Cs will outlast
Bs. The consideration rule is nothing more than an adaptive
foraging strategy for maximizing the net energy extracted from
the environment. |