Warm-Blooded Plants: Zero-g, Zero-T, and Zero-P

There are three principal obstacles to be overcome in adapting a terrestrial species to life in space. It must learn to live and be happy in zero-g, zero-T, and zero-P, that is to say, zero-gravity, zero-temperature, and zero-pressure. Of these, zero-g is probably the easiest to cope with, although we are still ignorant of the nature of the physiological hazards which it imposes. To deal with zero-T is simple in principle although it may be complicated and awkward in practice. Fur and feather...

 Make Mistakes

For evolution, which knows nothing, the steps into novelty are blindly taken by mutations, which are random copying “errors” in DNA. Most of these typographical errors are of no consequence, since nothing reads them! They are as inconsequential as the rough drafts you didn’t, or don’t, hand in to the teacher for grading. The DNA of a species is rather like a recipe for building a new body, and most of the DNA is never actually consulted in the building process. (It is often called “junk DNA” ...

 Dolphins have Genes for Smelling

Another curious tale of dead genes involves our sense of smell, or rather our poor sense of smell, for humans are truly bad sniffers among land mammals. Nevertheless, we can still recognize over 10,000 different odors. How can we accomplish such a feat? Until recently, this was a completely mystery. The answer lies in our DNA—in our many olfactory receptor (OR) genes. [...] Our own sense of smell comes nowhere close to that of mice. One reason is that we express fewer OR genes—only about 40...

 Vestigial GLO Pseudogene

And the evolutionary prediction that we’ll find pseudogenes has been fulfilled—amply. Virtually every species harbors dead genes, many of them still active in its relatives. This implies that those genes were also active in a common ancestor, and were killed off in some descendants but not in others. Out of about 30,000 genes, for example, we humans carry more than 2,000 pseudogenes. Our genome—and that of other species— are truly well populated graveyards of dead genes. The most famous huma...

 DNA as Evidence of Common Ancestry

By sequencing the DNA of various species and measuring how similar these sequences are, we can reconstruct their evolutionary relationships. This is done by making the entirely reasonable assumption that species having more similar DNA are more closely related—that is, their common ancestors lived more recently. These molecular methods have not produced much change in the pre-DNA-era trees of life: both the visible traits of organisms and their DNA sequences usually give the same information ...