Expert: Barbara Silber - 12/21/2005

Question
They're not homework!

1. Evolution supposes a time when inorganic molecules became capable of reproducing. My first question is, doesn't this imply that no organism contains *any* information other than that necessary to optimize its reproductive chances and then reproduce? This sounds reductionist, but (for example) in the case of a bacterium, apart from adaptative changes, everything it does is geared to reproduction...is that right?  

2. Many traits (height) are normally distributed. Are you aware of any explanations that tie normality to evolution? Naively, you might expect a linear distribution so that all heights (e.g.) can compete...  

Thanks for any insight (or refs). Daniel  

Answer
Dear Daniel,

Bacteria have genes that allow the organism to metabolize molecules. "Eating" may be considered an activity in itself. Some bacteria are motile; motion being another activity. Or you might say that everything an organism does is to make another generation. Does the chicken exist only to make another egg?
As one moves to eukaryotic cells there is much genetic material for which its function is still unknown. There is horizontal transfer of genetic material (Lynn Margulis) sometimes by viruses. Thus there can be much genetic material that could be called neutral as far as providing a selective advantage for the organism as well as deleterious genes. Think of the gene for sickle hemoglobin. Two copies lead to sickle cell anemia while one copy gives resistance to malaria.

Normality is a result of several factors: genetic and environmental.The more factors in a large population the smoother is the resulting curve. Always it is the environment that acts selectively on a population.

I hope that this helps you.

Barbara Silber