Birds: What you thought you knew about their evolution is ... wrong?

From both Science Daily and New Scientist comes the word that, in the words of New Scientist's Bob Holmes (June 26, 2008),

A new study – the largest analysis of birds to date using modern genetic methods – has turned up numerous surprising relationships that will force biologists to reevaluate much of what they thought they knew about avian evolution.

[ ... ]

This new tree contains several notable surprises. For example, falcons are more closely related to songbirds than to other hawks and eagles. The closest kin of the diving birds called grebes turn out to be flamingos. And tiny, flashy hummingbirds, according to the new tree, are just a specialised form of nighthawks, whose squat, bulky bodies make them an unlikely cousin.

and in the words of Science Daily, whose drudges toil nameless (June 27, 2008):

The results of the study are so broad that the scientific names of dozens of birds will have to be changed, and biology textbooks and birdwatchers' field guides will have to be revised. For example, we now know that:

Birds adapted to the diverse environments several distinct times because many birds that now live on water (such as flamingos, tropicbirds and grebes) did not evolve from a different waterbird group, and many birds that now live on land (such as turacos, doves, sandgrouse and cuckoos) did not evolve from a different landbird group.

Similarly, distinctive lifestyles (such as nocturnal, raptorial and pelagic, i.e., living on the ocean or open seas) evolved several times. For example, contrary to conventional thinking, colorful, daytime hummingbirds evolved from drab nocturnal nightjars; falcons are not closely related to hawks and eagles; and tropicbirds (white, swift-flying ocean birds) are not closely related to pelicans and other waterbirds.

Shorebirds are not a basal evolutionary group, which refutes the widely held view that shorebirds gave rise to all modern birds.

And, summing it up,

"With this study, we learned two major things," said Sushma Reddy, another lead author and Bucksbaum Postdoctoral Fellow at The Field Museum. "First, appearances can be deceiving. Birds that look or act similar are not necessarily related. Second, much of bird classification and conventional wisdom on the evolutionary relationships of birds is wrong."

Yeah. Wrong.

Or maybe not. This analysis depends on certain assumptions about bird genomes - and the assumptions may not be correct.

Here is what we now know for sure: No one living has any sure idea how different types of birds originated. Fanatics of one method clash with the fanatics of another.

And people wonder why there is an intelligent design controversy ...

Molecular clock - right twice a day?

2006 and 2007 have been years in which a number of key science papers addressed things we know - that ain't so. One story is the serious challenges to the long contested "molecular clock" theory.

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In the science literature, many adjustments are offered to make the fossil record and molecular data match. Of course, some adjustment is certainly inevitable, but after a while a question arises. One can live with a clock that is routinely ten minutes slow. But if it is variably slow, slower at some times than others, there may come a point when one asks, why consult a clock anyway? Or, more to the point, should this device properly be called a clock?

Read the rest here.

Note: I disabled comments for this post. Until the Comments thing at Design of Life is fixed, go to Uncommon Descent if you want to comment.

Molecular clocks: Right twice a day?

Jeffrey H. Schwartz of the University of Pittsburgh's Departments of Anthropology and History and Philosophy of science and Bruno Maresca of the Department of Pharmaceutical sciences at the University of Salerno, Italy, have state that "there is no basis" for the view that a "molecular clock" (a presumed calculable rate of evolution) can determine the evolutionary history of a species. In an interesting and mostly quite readable paper published in Biological Theory (1(4) 2006, 357-371, and available online, Schwartz and Maresca show how fossil findings and molecular clocks have simply not matched.*

For example, in reviewing an attempt to make sense of human-ape differences, they write,

First among the inconsistencies is the admission that the accepted model of molecular change and its phylogenetic interpretation were assumptions, and then the declaration that, since these assumptions were widely accepted, one could embrace them as truths. But they are assumptions and testable.

They end up questioning whether the molecular clock theory is even tenable. It appears to have been held because it provides information, but as the information comes from untested assumptions, it is of unknown worth.

(*To see what this means, suppose you tried to construct a timeline for family events based on the assumption that your grandmother was born in 1924 - because her birth certificate say so. But when her age is given in other dated official documents, she seems to have been born in 1926. And everyone who could help you straighten out the problem is dead. Your choice of birth date will affect the timeline, especially when you are dealing with events for which your source recalls only, "That happens when your grandma was 47 ....")

This paper is must reading for people who think that we know much for certain about human evolution. As the Eurekalert press release notes,

..., it is not only the current molecular theory that intrigues Schwartz, but the failure of the scientific community to question an idea that is more than 40 years old: "The history of organ life is undemonstrable; we cannot prove a whole lot in evolutionary biology, and our findings will always be hypothesis. There is one true evolutionary history of life, and whether we will actually ever know it is not likely. Most importantly, we have to think about questioning underlying assumptions, whether we are dealing with molecules or anything else," says Schwartz.

(Note:Jeffrey H. Schwartz should not be confused with non-materialist psychiatrist Jeffrey A. Schwartz, lead author of The Mind and the Brain. )

Check out my book on the intelligent design controversy, By Design or by Chance?.