Some of us are familiar with using DNA to determine parentage of domesticated plants, animals, or indeed children, for example finding the parents of prized wine grapes by sequencing them.
Classic evolutionary trees were drawn by Haechel, and there are several on Wikipedia.
I was surprised to see how different a quantitative tree like the one at right is from a qualitative one or the traditional one from grade school.
The quantitative tree comes from analysis of the 16s rDNA which is an important ribosome enzyme. Its function has been preserved since before the latest common ancestor of all existing plants and animals, and deviations in it provide a measure of evolution.
On this chart one change per base pair is about 8 centimeters along the line. This is from "Tree of Life" published by Norm Pace in 1997. See this site. Pace is at U of Colorado where Michelle studies.
People are covered under homo as in homo sapiens and are on the bottom hook near the left. We are right next to coprinus, which is a kind of mushroom, and zea which is a family of grasses that includes corn (maize). Other mammal species are going to be even more closely related.
The implication is that a great deal of evolution occurred prior to the differentiation between plants, animals and fungus.
Cynical biologists assert that yeast or oak trees are just as evolved as people, but simply for different things. I say, why not put people on top of the tree? Something has to be on top, and most everyone is going to try to find homo sapiens -- put them on top to make it easy.
The second point is that mammals and "higher" plants are getting a lot of differentiated performance out of some fairly similar genes.
This makes me wonder about saving rain forests for genetic diversity. There is probably more genetic diversity in pond scum than in a forest of trees.
Dad, everything else on the planet has been evolving as long as we have, so yes, we are all similarly "evolved." There is no top to the tree. It is more like the coral of life (I read this today somewhere), where everything primitive and ancestral is gone, and all you have on earth at any given time are current evolutions on any given line. Truth. Not cynical biologists, but logical ones. Keep in time that the changes/site is not related to time.
ReplyDeleteIn the microbial world, the only things that matter are the physical characteristics of the environment; ie ions, temp, O2 content, etc. In that sense, you can imagine many differnt microenvironments occuring in a place as varied as the rainforest. There are trees to live on, animals to live on and in, the different layers of soil. Microbes even live inside of stuff like rocks. And these would all be different kinds of microbes, that are adapted to their particular environments. Of course, there are microenvironments in a pond too, but I bet you can find various ponds in the rainforest as well, that aren't necessarily going to have the same microbes as a pond elsewhere.
Michelle, I don't disagree with anything you are saying especially that all evolutionary lines have been evolving for the same length of time.
ReplyDeleteThere is a big leap from Pace's tree to a creationist's notion of special creation and the biblical notion with an inherently special place for people. What is interesting is how close people are to mushrooms and grasses compared to the total range of diversity.