Sunday, 29 July 2012

Biology stuff from the week 23-29/7/12

[video] Dyscalculia - what is it - and how does it effect people? - Numberphile

Because it involves duplicate use of the same area of the brain, it is much more difficult to multi-task two visual tasks, than it is a visual and an audio task.
This makes it more dangerous to text and drive, than it is to talk and drive, for example.
"Alarmingly, though, people who tried to do two visual tasks at the same time rated their performance as better than did those who combined a visual and an audio task - even though their actual performance was worse."
A possible link between the visual area of the brain, and emotional experience, leading to happiness despite lack of performance?

"Researchers have been able to compare the human genome to the recently decoded genetic sequence of the invertebrate amphioxus, a tiny creature still found in our seas and which can be regarded as a 'distant cousin’ to our species."
Amphioxus has a spinal cord, bunches of muscles, and branchial arches where we have faces, but it does not have bones, a brain, a face, or a heart.
We, all other mammals, reptiles, birds, amphibians, and backboned fishes, have these features, because of a phase in our evolutionary history, ~500 million years ago, in which our genome duplicated - twice - which enabled far more control over physiological development.
When the control breaks down, in our more complex bodies, conditions such as diabetes, cancer, and neurological disorders develop.
Comparison of post-quadruplication genomes with amphioxus' genome will enable biologists to infer how these conditions arise, empowering us to deal with them more effectively, or prevent them from arising in others.

How do sharks keep their teeth in such good nick?
Chemical analysis of the teeth of Mako and Tiger sharks has revealed a high density of fluoride, in the form of fluoroapatite, in the outer part.
Human teeth are formed with hydroxyapatite, but this gets soft in watery environments, which is why the sharks have evolved the use of fluoroapatite.
Both teeth structures achieve the same overall hardness, however, because teeth that are too hard have the drawback of brittleness - they shatter easily.
Lack of fluoride can be a significant problem with tooth softness in humans, too, which is why it is often used in tap water (the fluoride in toothpaste can not be ingested easily, and can not benefit bones)

Whole genome sequencing of hunter-gatherers has revealed high genetic diversity, caused not just by divergence in adaptation to different environments, but also introgression - inter-breeding with lineages that are descended from ancestors of humans e.g. neanderthals and other hominids.

Increasing dopamine in the brain's frontal cortex increases self-control, reducing impulsivity, and lowering the risk of reckless behaviour.
It is a noted characteristic of people who 'habitually' commit crimes, that they are more impulsive than most, and so control of dopamine in the frontal cortex might enable them to avoid crime in future.

Are Polar and Grizzly (Brown) bears really distinct species?
For 6 million years, Ursus Maritimus (Polar) and Ursus Arctos (Brown) bears have interbred, but remained largely geographically separate.
As the polar populations dwindle, and continental populations encounter more Grizzlies, we might see more Polar-Grizzly hybrids wandering Canada and Russia.

Why is it that stressed people are more likely to resort to familiar habits, and less likely to achieve their goals, despite them?
It seems the stress hormones hydrocortisone and noradrenaline shut down the activity of brain regions for goal-directed behaviour, leaving the habit regions unaffected.
This makes it difficult for them to pursue their goals, and so they are more likely to fail. Trying to dump a bad habit? Avoid stress, and you'll be more likely to succeed.

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