Excessive hygiene lets the immune system run amok

29 Thursday Mar 2012

Posted by sedeer in Bacteria, Immunology, Microbiology

Tags

Allergy, animals, Asthma, biology, colitis, Health, Hygiene Hypothesis, Immune system, Mouse, Popular science

Since moving to Finland, I’ve become accustomed to asking guests whether they have any allergies before I prepare dinner. I grew up in the developing world where allergies and asthma seem to be much less common than they are here; in fact, various studies have found higher rates of allergy and autoimmune conditions in developed than developing countries. One explanation for this is the “hygiene hypothesis“, which proposes that excessive hygiene early in life can affect the development of the immune system and result in allergic conditions and autoimmune diseases in later life. In a recent study appearing in Science, a team of scientists in Germany and the United States present evidence supporting the hygiene hypothesis and the importance of an early challenge to the immune system.
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Mammals didn’t have to wait for the dinosaurs to die out

24 Saturday Mar 2012

Posted by sedeer in Dinosaurs, Evolution, Mammals

≈ 1 Comment

Tags

adaptive radiation, animals, Cretaceous–Tertiary extinction event, dinosaur, diversity, mammal, Popular science, teeth

A study recently published in Nature challenges the prevailing wisdom that the extinction of the dinosaurs paved the way for an explosion of mammalian diversity. By studying the fossils of a group of mammals called multituberculates, the researchers have cast doubt on the traditional view of dinosaurs constraining small, shrew-like mammals to a secondary role as nocturnal insectivores. Instead, this group seems to have diversified millions of years before the dinosaurs died out.
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Natural selection: On fitness

20 Tuesday Mar 2012

Posted by sedeer in Evolution, Natural Selection

≈ 5 Comments

Tags

biology, Darwinism, Education, evolution, fitness, natural selection, Popular science, replicator, science, selfish gene, tautology

For the third part in my series about natural selection I’d like to address the concept of fitness. Thanks to the phrase “survival of the fittest”, fitness is quite a prominent idea in the popular perception of evolution. It was originally coined by Herbert Spencer after he read On the Origin of Species; Darwin adopted the phrase in later editions and it’s been popular ever since. Unfortunately, this glib phrase has often eclipsed a more accurate depiction of evolution, leading to some common misunderstandings. This confusion arises because “fitness” has a different meaning in evolutionary biology than it does in general usage. (Have a look at the earlier posts in this series if you haven’t already read them; the first was about the different modes of natural selection and the second discussed selection mechanisms, focusing on sexual selection in particular.)

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Social wasps are specialists at recognizing faces

16 Friday Mar 2012

Posted by sedeer in Evolution, Hymenoptera, Insects, Mind

≈ 3 Comments

Tags

animals, biology, Cognition, evolution, face, Facial recognition system, Insecta, Paper wasp, Popular science, science, Wasp

There’s lots of evidence that humans have a specialized mechanism for identifying and responding to faces; for example, people with a condition called prosopagnosia have difficulty recognizing faces but not other objects. A few years ago, researchers showed that individual paper wasps of the species Polistes fuscatus recognize each other’s faces; the same team has now gone on to show that, like humans, P. fuscatus accomplishes this via a specialized mechanism for facial recognition rather than through general shape or pattern recognition. This story is an excellent example of a complex cognitive ability being exhibited by a creature with a relatively simple nervous system.

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Redheads and pain: science or sensationalism?

12 Monday Mar 2012

Posted by sedeer in Genetics, Humans

≈ 2 Comments

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animals, biology, Capsaicin, Human, Melanocortin 1 receptor, Pain, Popular science, Red hair, redhead, Redheads, science, science and society, Science communication

I’ve recently come across some press coverage reporting research by Danish scientists which has shown that “redheads feel pain differently than the rest of us”. I read the paper and thought it would be nice to write something short about it here, both for the change of tone and to give my own perspective on it.

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Natural selection: selection mechanisms, sex, and the brain

08 Thursday Mar 2012

Posted by sedeer in Evolution, Natural Selection

≈ 4 Comments

Tags

biology, brain, Education, evolution, natural selection, Popular science, science, selection, sex, sexual selection

This is second part in my series on natural selection. In the first part, I discussed different modes of selection; in this post, I’ll explain an important mechanism of natural selection which probably doesn’t get enough attention in basic biology courses. The idea, called sexual selection, dates back to Darwin, who dedicated over half of one of his books (The Descent of Man and Selection in Relation to Sex) to the subject. Sexual selection is based on the struggle to reproduce rather than the struggle to survive; this already gives us a hint that the term “fitness” has a different meaning in evolutionary biology than it does in common speech, which is a subject I’ll get to in a later part of this series.

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