Biology Reference
In-Depth Information
SPECULATIONS OF GENETIC ENGINEERING
What if, through the use of genetic engineering, an animal was created that
would feel no pain and have no fear? What would be the ethical implications
of this? The work of Chen et al. (1994) showed very clearly that knock-out
mice with no fear when mixed with unfamiliar mice caused serious welfare
problems due to fighting and injury.
In contrast, selecting for extreme docility with conventional breeding
methods could cause similar problems. Ranchers have observed that placid
Hereford bulls spend more time fighting with other bulls to determine
their social rank compared with flighty, excitable Salers bulls. The more
excitable animals are too fearful to fight. The second author has made simi-
lar observations in horses. The calmest horse on a pasture is more likely to
bully the other horses. Timid horses avoid a confrontation that could lead to
injury. There may be an optimum temperament between extreme docility
and flightiness. Motivation is complex. In Chapter 8, Faure's research shows
that fear is not a simple trait. Fear behaviors may look similar but have dif-
ferent motivations. For example, feather pecking in hens is probably misdir-
ected foraging behavior instead of true aggression. Cattle and pig breeders
need to select for a calm temperament and cull individuals that panic when
confronted with novelty, but it may be a mistake to select for the absolutely
calmest animals. An extremely docile cow may not take care of her calf (see
Chapter 5). In the Chen et al. (1994) experiment, increased defensive aggres-
sion only occurred in mice heterozygous for the knock-out gene. Mice with
both calcium/calmodulin kinase II genes knocked out had overall attenuated
aggression and many other abnormal behaviors. The behavior in these mice
differed depending on whether one copy, or both copies of the gene were
knocked-out. This research clearly shows that knocking out genes is not
going to provide clear-cut results. As with natural breeding, traits are linked.
The behavior of an animal is the sum of a complex interaction between
inherited traits and those traits' interactions with the environment.
GENETIC DIVERSITY
Another serious concern brought up by ethicists and geneticists is the prob-
lem of restricting the gene pool. This problem is not limited to genetic engi-
neering. Many scientists are concerned about the loss of genetic diversity
( Notter, 1996; Cundiff et al., 1996 ). Larry Cundiff, a researcher who works
for the U.S. Department of Agriculture, stated that pig breeds in China are
more heterozygous. Preserving the genetic diversity of Chinese pig breeds is
important.
The loss of genetic variability in agricultural plants and animals could
result in disaster if disease struck a susceptible high-producing genetic line.
Nothing is free. If one selects for just one trait there is usually a price to be
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