>> Friday, August 20, 2010
Shakespeare asked: Also, my daughter has a question, sparked by our birds and bees talk: Is it possible for a person to have a child without sperm and egg coming together? Why or why not? Has it ever happened, or might it become possible in the future?
There are critters out there that manage to reproduce without male involvement. The primary process is called parthenogenesis and it's not a common function. In general, particularly in the higher animals, sexual reproduction (sperm and egg type fertilization) is more advantageous for genetic diversity. Under general circumstances, an ovum, the egg as it were, contains only half the genetic material necessary for a new creature. Humans, for example, have 26 pairs of chromosomes, with each parent providing half of that pair. Without fertilization from a sperm, it isn't viable.
But there are exceptions. Aphids, for example, are capable of reproducing from a single female, no male. Most of the time, these aren't clones but rather combinations of eggs together so that it contains mixtures of pairs just like the mother and pairs of chromosomes that are identical. Usually, the results are always female (if males are determined by an XY configuration). This and related processes are not restricted to insects, though the vast majority of animals prone to this are insects and other invertebrates, but it's been seen in lizards, birds and even sharks.
There's even a parasitic bacteria that can cause it in insects.
It has not been observed in mammals; however, it can be artificially triggered several mammals and it can cloning are theoretically possible even for humans.
Multiple generations from a single genetic source, however, can be very dangerous. Frequently, complex animals have "bad alleles," recessive traits that can be deadly or debilitating if they manifest. Because they are so destructive, they are rare enough that creatures rarely have an offspring with both - thereby preventing manifestation (as "anything else" is dominant). If, however, one starts duplicating chromosomes as pairs, the chances of having a bad allele manifest increase sharply.
I have to tell you, I'm still fond of making offspring the old fashioned way.
If the Mother shows up, she'll probably correct my answer in a dozen ways and can probably expand it as well.
(She also asked: BTW, where do I get one of those novel progress thingies? I want to put one on my own blog... since I'm now actually working on something. Here are some sources: