Posts Tagged ‘Science’

Puggles

May 7, 2008

I have a young cousin — and I thank you, Andrew — who recently introduced me to the word “puggle” which I think is a fine word. It means baby platypus.

I see that dog breeders with too much time on their hands have also introduced a hybrid dog breed by the same name, but I will use the word as it should be used, to describe baby platypuses. If dog breeders want to cross pugs and beagles, let them find a new name for the result.

Having just learned the word, I was anxious for an opportunity to use it, but a blog about birds seemed an unlikely place. But today comes news from the science magazine Nature that scientists have successfully mapped the entire genome of the platypus. That is of interest to birders because some of the genes found in the platypus were, until now, known only in birds. Said differently, birds and platypuses are distant relatives, sort of like Andrew and I.

For instance, platypuses share with chickens a gene for a type of egg-yolk protein. Puggles are born from eggs; but treated to mothers’ milk, like mammals, as soon as they are born. They possess microRNAs which chickens have, plus different microRNAs which only mammals possess. And, unlike mammals, platypuses have two matches for what scientists call the ZPAX genes which, until now, had been found only in birds, fish and amphibians. These are the genes that determine the sex of puggles. Ten sets of chromosomes do that job instead of two which is enough for humans: An X and a Y result in a baby boy; two Xs result in baby girls.

Platypuses have X chromosomes, but they are much more like the Z chromosomes found in birds than the usual mammalian X. “The sex chromosomes are absolutely, completely different from all other mammals. We had not expected that,” said one of the scientists. And the Y chromosome, which platypuses possess, seems to have nothing to do with gender.

Platypuses are “monotremes.” (From the Greek monos ‘single’ + trema ‘hole’) Analogous to avian cloacas, they have but one opening for the intestinal, urinary, and genital tracts.

Platypuses are the oldest surviving branch of all mammals on the earth today. They got their start on the ancient continent of Gondwana which split into modern Australia and South America. Monotremes on South America died out but platypuses survive on the East coast of Australia and on Tasmania. They lay eggs, but make milk for their babies; they have fur coats and an aquatic life style; they forage for food underwater using an electro-sensory system in their duck-shaped bills. The males grow spurs on their rear legs which produce venom strong enough to kill dogs and incapacitate humans; a venom remarkably similar to that produced by venomous snakes.

To quote the scientists again, “There is nothing quite as enigmatic as a platypus.” But don’t take their word for it. Here is Odgen Nash on the subject:

The Platypus

I like the duck-billed platypus
Because it is anomalous.
I like the way it raises its family
Partly birdly, partly mammaly.
I like its independent attitude.
Let no one call it a duck-billed platitude.

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You can see video from Nature here and read newspaper articles here and here.

Birds Smell Predators

April 28, 2008

Today we get the stunning news that birds can smell predators. Some overwrought scientists ladled ferret smell into nest boxes of Blue Tits in Spain. Eight-day old chicks were living in the nests at the time. The parents of the chicks were afraid to go into the boxes to feed the chicks after the fraud.

Really. Probably thought there was a ferret in there. Silly birds.

The ingenious scientists deduce from video cameras aimed at the nest box that, “birds are able to detect the chemical signals of predators.” The evidence? The parents flew to the nest box as often as they did before the fraudulent ferret odor, but went into the nest box less frequently and left quickly. I wonder why.

Oh, wait. The scientists figured that out also. “By spending less time in the nest box, the parents lessened the risk of predator attack while still feeding their chicks.”

Five days later, afraid the mendacious ferret smell might be losing vitality, the demoniac scientists freshened it up, just to see if the ferret perfume, “. . .had an effect on the chicks’ physical condition.” According to the intrepid scientists, it did not.

They forgot to ask about the psychological condition of the family.

Tastes Like Chicken

April 25, 2008

Lets assume you go to visit friends over the weekend for a barbecue and they grill you a nice Tyrannosaurus Rex steak. According to the latest scientific research, it would probably taste a lot like chicken.

Barbecue

We’ve written here before , in our bird sex series, about the evolutionary links between modern birds and dinosaurs. Until recently this hypothesis was based mainly on anatomical similarities between dinosaurs and birds. (Size obviously not being one of the similarities.)

68 million years ago a Tyrannosaurus Rex died in present-day Montana. Protein (collagen) from deep within one of his bones — probably, but not certainly, uncorrupted — has been analyzed, yielding genetic confirmation that birds are the closest living relatives of dinosaurs. T-rex, ostriches and chickens all had the same — as yet, unidentified — ancestor. It probably tasted like chicken too.

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The painting reproduced above is Eric Fischl’s Barbecue which we would happily steal from Steve Martin’s private collection. In fact, had Mr. Martin the decency to invite us to his home we might have done it aready. It is true that Steve Martin does not know us but that is no excuse. Who does he think he is anyway, some kind of big celebrity or something? Anyway, it was the only barbecue theme painting we could think of in time to get this post to press.

The complete article about T-rex appeared in today’s Science magazine. (Expensive subscription, which we don’t have, required. Who do they think they are, some kind of scientists?)

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UPDATE – April 28, 2008

For more on the evolution of birds here is a real scientist discussing evidence of the evolution of feathers.

Morning Coffee

April 6, 2008

I’m not worth a damn until after my second cup of coffee in the morning. Even the dogs know how useless and cranky I am; they stay away from me. When I first wake up I am grouchy and stupid. After the coffee, I am amicable and brilliant. Just ask me — right after that second cup of coffee. Don’t talk to me before then. I think it’s the caffeine which turns me into a human being. (And why is that an “e” after the “f” in caffeine instead of an “I”? Don’t coffee drinkers follow the rules?)

There is good news for us coffee drinkers at the BBC. Coffee is good for us. It may well help delay or even prevent the onset of many dementias. Mammals have a “blood-brain barrier” which protects our brains from many of the substances carried by the blood. It is a membrane between the capillaries and the brain itself. Composed of densely packed endothelial cells, the membrane prevents most substances from reaching the brain. All the body’s capillaries have this membrane but it is much more tightly packed in the head. Only substances the brain needs, like oxygen, carbon dioxide, some sugars and amino acids are allowed in. As is ethanol, which explains why booze is literally a mind altering substance. It may also explain why caffeine may not protect against alcoholic dementias even while protecting against others such as Alzheimer’s. (But red wine lowers cholesterol so my glass or two of red wine in the evening is also good for me. I love science!)

But high levels of cholesterol in the blood make the blood-brain barrier leak. Nobody knows why but cholesterol softens up the blood-brain barrier which contributes to dementia. But — bring up the trumpets — caffeine disrupts the ability of the cholesterol to attack the blood-brain barrier. Just a cup of coffee a day helps and, if one cup is good, four is better.

That’s the good news. From the New York Times comes a fly in the caffeine. Our grocery shopping, especially in the winter and spring is killing songbirds and raptors. The beautiful and justly famous Bobolink, Swainson’s Hawks, Barn Swallows and Eastern Kingbirds are a few of the victims of North Americans’ desire for fresh fruit and fresh vegetables year-round. The Latin American countries from whom we get these fruits and vegetables are spraying huge amounts of pesticides long outlawed in the U.S. on those crops and the pesticides are killing birds which migrate to those Latin American fields in the winter. The birds are being poisoned to keep us in fresh fruit. In one study half of the Bobolinks tested had, “drastically reduced levels of cholinesterase, an enzyme that affects brain and nerve cells — a sign of exposure to toxic chemicals.” Caffeine doesn’t help that.

bobolink photo

What does this have to do with our pleasant morning ritual of coffee drinking? We need to buy organic coffee. Here is what Dr. Stutchbury suggests:

What should you put on your bird-friendly grocery list? Organic coffee, for one thing. Most mass-produced coffee is grown in open fields heavily treated with fertilizers, herbicides, fungicides and insecticides. In contrast, traditional small coffee farmers grow their beans under a canopy of tropical trees, which provide shade and essential nitrogen, and fertilize their soil naturally with leaf litter. Their organic, fair-trade coffee is now available in many coffee shops and supermarkets, and it is recommended by the Audubon Society, the American Bird Conservancy and the Smithsonian Migratory Bird Center.

Done. Only organic coffee will be served in our home from this point forward. You’re welcome to stop by for some. But not until I’ve had my second cup.

Bird Sex, Part III

March 1, 2008

Dr. Olivia Judson, an evolutionary biologist who has a blog on the New York Times web site, recently asked one of the burning questions of modern science: Did Tyrannosaurus rex have a penis? Or two as some modern lizards do? Or, like most birds, none? (You can read her post here.) Modern birds may know the answer.

field_guide_trex.jpg

We know this question has been keeping you up nights and we’re happy to answer it.

Wait. Not so fast. First we need to set the stage. Five times in the known history of the planet mass extinctions wiped out most forms of life here. The biggest — the Permian-Triassic — happened about 251 million years ago, last Tuesday. (251 mya) The most well-known mass extinction was about 65 million years ago. (65 mya) This was the famous one, the Cretaceous Extinction, probably caused by an asteroid hitting the earth’s atmosphere somewhere above what is now the Gulf of Mexico. The resulting explosion vaporized everything nearby and sent up a cloud of dust so thick that it was decades before the sun shone through again. In the meantime almost all terrestrial life had starved or frozen to death, including the dinosaurs.

Not all life forms were wiped out. Obviously some survived; otherwise insufficient time would have passed for evolution to reach its pinnacle — the blogger.

A few bird ancestors lived through it. Specifically, two “superorders,” the Palaeognathae and the Neognathae. (There will be a test. ) Frankly, we know very little about how they came to exist before the extinction or how they survived it. About all we know for sure is that modern birds came from the two superorders, both of which came from dinosaurs. As Judson tells us, “Birds are more closely related to T. rex than they are to any living form.”

While we are fairly confident that birds evolved from dinosaurs we are not sure from which dinosaurs. One theory holds that birds evolved about 230 mya from Thecodonts. Another argues that birds developed from Theropods 150 mya. (Remember, there will be a test.) Still another asserts that birds arose from Dromaeosaurs about 110 mya. Which is correct depends on how dinosaurs learned to fly. Did they start by soaring or jumping or running after insects? More on that in a later post. Today we are concerned with sex, not flight.

As we discussed in our earlier posts about bird sex, which are here and here, most birds do not have penises. Procreation occurs when male and female birds touch their cloacae to one another. Only a few bird species possess penises. Some waterfowl and large flightless birds do. So do male crocodiles which, like birds, have cloacas; but also have a penis down which sperm passes on the outside, which is true for penis-owning birds as well. Crocodiles too descended from dinosaurs.

We’re close to the answer now. But first, we need to remind you that the fossil record does not answer the question about T-rex’s genitalia. The reason is simple: Except in a few mammals, penises consist of nothing but soft tissue which does not fossilize well. No fossil record of dinosaur penises exists. Which is why we look to birds for the answer.

Here is Dr. Judson’s answer:

The palaeos comprises the big flightless birds such as ostriches, emus, rheas, and cassowaries, as well as kiwis and an obscure (but flying) group of south American birds, the tinamous; the neos covers everything else. The palaeos have penises; like crocodiles, they keep them tucked into their cloacae. Again like crocodiles, the organ has an external groove for sperm. What’s more, the lineage leading to the other endowed birds, the ducks, geese, and swans, appears to have split off from that of the other neos relatively early.

This strongly suggests that the ancestor of all birds had a penis, and that at some point early in the evolution of the neognathous birds, the penis got lost.

Now you can get some sleep.

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Part I of this series.

Part II of this series

Feeding Birds in the Winter

February 14, 2008

tomlin_blue_tit_450x338.jpg

The New York Times this week reports here that non-migratory birds who have human supplied bird seed during the cold of winter do better than those which do not. Or at least English Blue Tits do. (No jokes please. This is not only science, it’s British science. That is a Blue Tit in the photo. Really.) In a study published recently in Biology Letters, the scientists fed Blue Tits peanuts throughout the winter of 2005-2006. Birds which were fed supplemental peanuts laid eggs about two and a half days earlier than birds which did not receive extra winter-time food. In addition, their chicks were more likely to survive. The study indicates that supplemental winter feeding of birds aids the species fed. Not studied was the impact, if any, on migratory birds passing through the area where the Blue Tits were fed.

Our conclusion: Feeding birds in the wintertime is good for the birds. It’s good for us too. Even if we are housebound for much of the winter, it is good to have a bird feeder and birds to watch. Reminds us that there is a world out there of which we are a part.

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Don’t forget that the Great Backyard Bird Count is this weekend.


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