Tag Archives: evolution

Why I have always liked Arthur Caplan…

Posted on by

I have been a fan of Arthur Caplan for a long time.  In medical school, I had the good fortune to study closely with several brilliant bioethicists including Baruch Brody and Tristram Engelhardt.  Since that time, I have remained interested in bioethics.  Arthur Caplan has been a leading voice in bioethics for a long time and often approaches topics in a no-nonsense manner.

A recent link (from John Pohl’s twitter feed) chronicle.com/blogs/conversation/2014/01/07/distinguishing-science-from-nonsense/ … and excerpt from Arthur Caplan addresses the need for a better appreciation of science; this short opinion piece ties together brain death, vaccines, evolution, and nutritional supplements:

A key reason for the poor performance of our children with respect to science is that American culture is both ignorant of and disrespectful to science.

As I write this, two women in ICUs in the United States are on life support despite having been pronounced dead by medical experts. These women, a teenager in Oakland, Calif., and a young woman in Fort Worth carrying a 14-week-old fetus when she died, were found to be dead on the basis of brain death. Both had their bodies maintained by machines (in Oakland it was with the support of her family; in Texas it was against family wishes). Neither the news media nor the medical profession seemed to be able to explain that brain death is truly death. Nor did the public seem inclined to listen, believing that somehow a miracle might occur.

At the same time as those cases emerged, a poll was released by the Pew Research Center showing that a third of Americans do not believe in evolution. They think that “humans and other living things have existed in their present form since the beginning of time.” Twenty-four percent acknowledge evolution but believe that a Supreme Being has directly guided life on earth.

And as I write this, flu season has begun. The federal Centers for Disease Control and Prevention estimates that last year 381,000 Americans were hospitalized because of the flu. They also estimate that the flu vaccine prevented 79,000 hospitalizations and 6.6 million illnesses. Yet a tiny cabal of kooks and know-nothings has gotten so much attention that barely half of all Americans get a flu shot.

The problem does not end there. The multibillion-dollar nutritional-supplements industry has no solid evidence for the efficacy of its products, while there are plenty of instances in which death and disability have been linked to poorly manufactured or mislabeled supplements. Yet our airwaves are full of ads and endorsements for this cornucopia of malarkey.

The point ought to be clear. Children are not going to flourish at science in a society that treats science either as something you can believe in selectively, something that is simply one point of view, or something about which anyone can have a credible opinion no matter how ill-qualified, dumb, or misinformed.

If we want to have a brighter economic future, then we need to start thinking about science education outside of our schools. We need editors who refuse to put fringe points of view on the air. We need scientists who see it as their duty to engage broader audiences—not just their peers—about their work. We need the training of scholars in the public understanding of science so that more voices are heard respecting science and the scientific method.

We need our courts to better vet who can speak for science. And we need more scientists as role models rather than the athletes and entertainers so put before the eyes of kids who may find it a bit hard to take chemistry, ecology, epidemiology, statistics, and geology seriously when their home life is filled with the musings of the casts of Duck Dynasty, Here Comes Honey Boo Boo, and Long Island Medium.

And we wonder why Johnny and Jane can’t distinguish science from nonsense.

Arthur L. Caplan is a professor of bioethics and director of the division of medical ethics at NYU Langone Medical Center.

Sugar-resistant bugs

Posted on by

“Evolution helps cockroaches lose their sweet tooth, increase survival”

An excerpt from the following link: Evolution helps cockroaches lose their sweet tooth, increase …  summarizes a recent study from Science below.  The findings provide further evidence of how bugs (along with microbial bugs) adapt; in circumstances where glucose can be lethal, bugs that are sugar averse have a selective advantage.

Have you ever wished you could just turn off your sweet tooth to help you resist that third piece of pie? For people, the downside of the deliciousness of sugar is simply feeling really full or gaining weight, but for cockroaches, their sweet tooth can be deadly.

The poisoned baits people set to kill roaches in their homes lure the unsuspecting insects in with sugar. But it turns out that the selective pressure of delicious, deadly traps throughout the environment has led to the rapid evolution of cockroaches that avoid sugar. They turned the sweet tooth off—or rather redirected it so it now tastes bitter.

A team of researchers from North Carolina State University published research this week looking at how the German cockroach, Blattella germanica, was able to adapt so quickly when surrounded by tasty insecticide. Sweet baits became popular for roach control in the mid-1980s, but several years later scientists began noticing a new behavioral trait: aversion to glucose, the most common simple sugar. The trait is heritable, and cockroaches with it avoided the baits. In areas treated with these traps, the roaches without a sweet tooth had much better survival rates than the roaches that lacked this new adaptation.

Insects’ sense of taste comes from hair-like structures on the mouthparts that contain nerve cells called peripheral gustatory sensory neurons. Insects have four “tastes”—sweet, bitter, water, and salt. Typically, foods that trigger the sweet neurons led the insects to eat, while foods that trigger the bitter neurons cause them to avoid that food.

The scientists, Ayako Wada-Katsumata, Jules Silverman, and Coby Schal, suspected that a change in the bitter and sweet sensory systems led to the glucose aversion trait. When they compared the sugar and bitter sensitivities of the averse roaches with the wild type, they found that the glucose triggered the same neurons as caffeine — very bitter. However, both groups of roaches still ate fructose, another simple sugar molecule, at the same rates.

Sampling wild cockroaches, they found glucose-averse individuals in seven out of 19 populations. The sensory responses in the native cockroaches mimicked the lab experiments, with caffeine and fructose responses remaining normal and glucose triggering the bitter system instead of the sweet. This shows that a very similar glucose aversion mechanism arose in multiple populations.

What kind of mutation led to this adaptive behavior? The researchers suspect that one or more mutations modified the bitter sensing system to react to glucose. For populations surrounded by sweet poisons, this mutation offers a serious evolutionary advantage. However, growth and reproduction of the glucose-averse roaches is slower than the normal population, so the mutation only functions as an adaptation in the face of attempted pest control.

The more we try to poison the roaches, the greater the advantages of being a cockroach that thinks sugar tastes bitter, and the more common this mutation will become. We probably need to find a new type of insecticide.

Science, May 2013. DOI: 10.1126/science.1234854

Related blog entries: