Great Tit Telomeres, Baby Talk, Brainy Birds

Great Tit Telomeres, Baby Talk, Brainy Birds

This morning, I have three interesting scientific findings related to bird for you. First, birds may age more quickly in urban environments. Maybe everything ages more quickly in urban environments. Second, baby birds learn, or perhaps are taught, song as adults alter the way they produce the song around babies, chirping slowly and clearly, as it were. Third, which we already suspected, bird brains are adjusted to provide extra smartness in a way not seen in mammals.

City Great Tit (Parus major) telomeres shortened.

Every time a gene is replicated, or really, a chromosome (during cell division), a bit of the end of a gene may be lost, owing to the way this process happens. Telomeres are repetitive sequences of genetic material sitting at the ends of genes. The Telomere does not contain useful genetic information, but rater, acts as a buffer. A bit of the telomere part of the gene can fall off without a problem. But as cells replicated again and again, you eventually run out of telomere, and the gene may become broken. This is part of the process of aging.

So, aging can be observed by measuring telomere length. The less telomere, the more aging, independently of time.

Scientists studies the telomeres of city dwelling Great Tits (Parus major). They used Great Tits from non-urban and urban areas, and mixed them up through breeding, to rule out any possible family history of telomere length. They found that cit dwelling Great Tits aged faster than expected.

Abstract

Urban environments are expanding rapidly, and with urbanization come both challenges and opportunities for wildlife. Challenges include combating the anthropogenic disturbances such as light, noise and air pollution and lower availability of natural food sources. The benefits are many, including the availability of anthropogenic food sources, breeding boxes and warmer temperatures. Thus, depending on the context, urbanization can have both positive and negative effects on fitness related traits. It is well known that early-life conditions can have lifelong implications on fitness; little is however known about development in urban environments. We reciprocally cross-fostered urban and rural nestling great tits (Parus major L.) to study how growing up in an urban versus rural habitat affected telomere length (TL)—a suggested biomarker of longevity. We show, for the first time, that growing up in an urban environment significantly shortens TL, independently of natal origin (i.e. urban or rural). This implies that the urban environment imposes a challenge to developing birds, with potentially irreversible effects on lifespan.

That’s from Urban environment shortens telomere length in nestling great tits, Parus major by P. Salmón, J. F. Nilsson, A. Nord, and S. Bensch, C. Isaksson, Biology Letters, Royal Society.

Baby Talk

In humans, adults (probably mainly mothers) do this thing called “motherese” which is talking in a way one would normally not talk to another adult, to a baby. You are certainly already familiar with this. Research done quite a while back suggests that this is adaptive. Babies learn certain aspects of langauge better if they get exposure to motherese.

Turns out that adult birds also alter their vocalizations to facillitate learning by baby birds.

Jon Sakata, a professor of neurobiology at McGill, says that songbirds learn vocalizations like humans learn speech. “Songbirds first listen to and memorize the sound of adult songs and then undergo a period of vocal practice–in essence, babbling–to master the production of song.”

Researchers have been studying song learning in birds for some time. But the degree to which social interaction with adult birds contributes to that learning has been unclear. That’s because, unlike this current work, past studies didn’t control for the time exposed to song and the presence of other birds.

In this study, published in the journal Proceedings of the National Academy of Sciences, a group of juvenile zebra finches was allowed to interact with an adult. Another group simply heard adult songs played through a speaker. After a brief period of “tutoring” the juveniles were house individually for months as they practiced their tunes.

Sakata and his team found that avian pupils who socialized with an adult learned the adult’s song much better. That was true even if the social tutoring lasted just one day. In analyzing why this would be so, Sakata and his team made a surprising discovery.

Adult zebra finches change their vocalizations when singing to juveniles. Sakata says just as people speak more slowly and repeat words more often when speaking to infants, so do these birds. “We found that adult zebra finches similarly slow down their song by increasing the interval between song phrases and repeat individual song elements more often when singing to juveniles.”

What’s more, the researchers found that juvenile birds pay more attention to this “baby talk” compared to other songs. And the more the juveniles paid attention, the better they learned.

More on this here, as well as some audio examples for you to listen to.

Bird Brains Packed With Neurons

Here’s the problem. Neurons are picky and inefficient. Had cells or organelles evolved, way back when, to handle “intelligence” rather than simple information signaling, they may have turned out differently, but that didn’t happen. A result of this evolutionary constraint is that later organisms that build complex neural processing organs (brains) to do advanced brainy things have to work with a cell type that is only fed with one kind of sugar, that requires a fair amount of coddling to operate, and that takes up a lot of space (one cell per bit of information). In humans, which have large brains, the brainy tissue uses up a disproportanate amount of our energy. In an infant, with a devloping brain that is out of proportion in size to it’s body compared to an adult, the total energy required to maintain the brain can be something close to half of the infant’s energy input. This is rather remarkable, when you think of it.

Bird, at least the ones that fly, can’t afford this kind of waste, so bird brains have evolved to be much more efficient than mammal brains. For example, some of that brainy tissue needed to be a singing, territory defending, mate seeking male bird is added during breeding season, and removed later when not needed. Can you imagine what it would be like if mammals could grow brain when needed, discarding it when not needed? Think about that for a moment …

Anyway, we now know that the forebrain of some birds is more densely packed than mammals (primates and rodents, anyway). I’m pretty sure this was already partly known or suspected, but this new research nails it down.

We investigated the cellular composition of the brains of 28 avian species, uncovering a straightforward solution to the puzzle: brains of songbirds and parrots contain very large numbers of neurons, at neuronal densities considerably exceeding those found in mammals. Because these “extra” neurons are predominantly located in the forebrain, large parrots and corvids have the same or greater forebrain neuron counts as monkeys with much larger brains. Avian brains thus have the potential to provide much higher “cognitive power” per unit mass than do mammalian brains.

From Birds have primate-like numbers of neurons in the forebrain by Seweryn Olkowicz, Martin Kocourek, Radek K. Lu?an, Michal Porteš, W. Tecumseh Fitch, Suzana Herculano-Houzel, and Pavel N?mec.