Sharon Begley's "Science Journal"

Re: Sharon Begley's "Science Journal"

Postby admin » Tue Oct 29, 2019 2:25 am

Yes, Evolution Still Has Unanswered Questions; That's How Science Is
by Sharon Begley
June 3, 2005; Page B1

Compared with fields like genetics and neuroscience and cosmology, botany comes up a bit short in the charisma department. But when scientists announced last week that they had figured out how plants grow, one had to take note, not only because of the cleverness required to crack a puzzle that dates to 1885, but because of what it says about controversy and certainty in science -- and about the evolution debate.

In 1885, scientists discovered a plant-growth hormone and called it auxin. Ever since, its mechanism of action had been a black box, with scientists divided into warring camps about precisely how the hormone works. Then last week, in a study in Nature, biologist Mark Estelle of Indiana University, Bloomington, and colleagues reported that auxin links up with a plant protein called TIR1, and together the pair binds to a third protein that silences growth-promoting genes. The auxin acts like a homing beacon for enzymes that munch on the silencer. Result: The enzymes devour the silencer, allowing growth genes to turn on.

Yet biology classes don't mention the Auxin Wars. Again and again, impressionable young people are told that auxin promotes plant growth, when the reality is more complex and there has been raging controversy over how it does so.

Which brings us to evolution. Advocates of teaching creationism (or its twin, intelligent design) have adopted the slogan, "Teach the controversy." That sounds eminently sensible. But it is disingenuous. For as the auxin saga shows, virtually no area of science is free of doubt or debate or gaps in understanding.

"Every scientific theory is constantly under scrutiny and has unknowns at its edges," says physicist Lawrence Krauss of Case Western Reserve University, Cleveland. "Singling out evolution makes it appear that evolution is suspect, which it isn't."

For instance, you can start a bar fight if you ask astronomers what the dark matter that pervades the universe is. But up-to-date textbooks rightly note that dark matter exists, even though its composition remains an enigma.

Physicists have been known to sputter in rage over the interpretation of quantum mechanics, which underlies all of modern electronics and often is called the most successful theory in the history of science (physicists aren't known for low self-esteem). Yet quantum mechanics also says the subatomic realm is inherently uncertain. It is impossible, even in principle, to predict when, say, a radioactive atom will decay. All you know is the probability, perhaps 50-50, that it will decay in the next hour. What has happened to the atom after an hour?

One camp holds that it exists in a fuzzy, indeterminate state until you peek at it, arguing that no phenomenon is a phenomenon until it is observed. Another holds that the atom decays in this world but remains intact in a new, parallel world. Controversy galore, but not enough to make anyone seriously doubt quantum theory.

Even some basics of physics are disputed if you dig deep enough. Introductory courses teach that mass is conserved, for instance. "But that couldn't be more wrong," says Frank Wilczek of Massachusetts Institute of Technology, who shared the 2004 Nobel Prize in physics. "Massive particles such as protons are built of quarks and gluons, which have zero mass [unless they are moving]. Mass is far from conserved."

The law that "for every action there is an equal and opposite reaction" isn't universally true either. "It fails for magnetic forces between charged particles," Prof. Wilczek says.

Teach the controversy? Then try the one over water. After the assertion that water's formula is H2O, add an asterisk: There is (controversial) evidence that it is sometimes H1.5O.

The funny thing about demands to "teach the controversy" in evolution is that creationists are focusing on the wrong things. They argue that evolution is wrong because there are no transitional fossils showing how one species evolved into another, for instance. But paleontologists have found fossils that are transitional between whales and their terrestrial ancestors, and between finned creatures and limbed ones.

Creationists also claim that evolution can't explain how small genetic changes could produce new species (rather than the same species with new traits, such as bacteria resistant to antibiotics). But the new field of "evo-devo" shows how minor genetic changes can lead to major structural ones, such as the presence or absence of wings or legs, notes biologist Sean Carroll of the University of Wisconsin, Madison.

Gaps in knowledge? Of course. Every ongoing field of science has them. Physicists can't explain why elementary particles have the masses and other traits they do, but that doesn't invalidate the basic theory of matter. It just means scientists have to keep trying. Say "God did it" if you like, but that isn't science.

Evolution is as well-established by empirical observation as other sciences. There is no serious debate that evolution happens, only deeper questions (left to college and graduate school), such as whether it proceeds gradually or in spasms. "It's dishonest to single out evolution," Prof. Carroll says, "when the very nature of science is to have unresolved questions."
Site Admin
Posts: 28148
Joined: Thu Aug 01, 2013 5:21 am


Return to Science

Who is online

Users browsing this forum: No registered users and 2 guests