A male fly approaches a flower, lands on top of what he thinks is a female fly, and jiggles around. He's trying to mate, but it isn't quite working. He has another go. Eventually he gives up and buzzes off, unsuccessful. ...
Plants & Animals
Mar 23, 2023
0
76
Plump and ponderous, tardigrades earned the nickname "water bears" when scientists first observed the 0.02-inch-long animals' distinctive lumbering gaits in the 18th century. Their dumpy plod, however, raises the question ...
General Physics
Aug 27, 2021
3
1406
Many lizards are phenomenal climbers. Their sharp, curved claws are ideal for clinging to tree trunks, rocks and other rough surfaces. However, in the precarious world of tree tops—filled with slippery leaves and unstable ...
Plants & Animals
Aug 5, 2021
0
611
When investors hedge a bet, they divvy their money between risky investments, which might make a large profit, and safe investments, which help ensure that not everything is lost in a market crash. The herpesvirus cytomegalovirus, ...
Cell & Microbiology
Jul 6, 2020
0
122
Scientists have learned a lot about evolution by studying fossils, by observing nature and, more recently, by unraveling the genetic code stored in DNA.
Evolution
Feb 26, 2019
4
138
Strong fists for defending ourselves and opposable thumbs for work as fine as threading a needle—hand specialisation is widely believed to have given humans a major evolutionary advantage.
Evolution
Jul 14, 2015
33
2306
For the first time, scientists have been able to paint a detailed chemical picture of how a particular strain of bacteria has evolved to become resistant to antibiotics. The research is a key step toward designing compounds ...
Biochemistry
Apr 28, 2011
12
0
(PhysOrg.com) -- Scientists studying imitative behavior have found that, just like people, dogs learn quickest by automatic imitation. Apart from the budgerigar, this is the first time automatic imitation has been demonstrated ...
(PhysOrg.com) -- Sticky is good. A University of California, San Diego bioengineer is the first author on an article in the journal Science that provides insights on the “stickiness of life.” The big idea is that cells, ...
Biotechnology
Apr 10, 2009
2
0
Exactly how does coral make its skeleton, a sea urchin grow a spine, or an abalone form the mother-of-pearl in its shell? A new study at the Advanced Light Source at the Department of Energy's Lawrence Berkeley National Laboratory ...
Bio & Medicine
Mar 26, 2024
0
26
Major depression is the leading cause of disability worldwide, and in 2000 was the fourth leading contributor to the global burden of disease (measured in DALYs); it is also an important risk factor for suicide. It is understandable, then, that clinical depression is thought to be a pathology — a major dysfunction of the brain. Yet the epidemiology of clinical depression is something of an outlier when compared to the epidemiology of major dysfunctions of other organs like the heart, liver, lungs and kidneys[citation needed]. In most cases, rates of organ dysfunction increase with age, with low rates in adolescents and young adults, and the highest rates in the elderly. These patterns are consistent with evolutionary theories of aging which posit that selection against dysfunctional traits decreases with age (because there is a decreasing probability of surviving to later ages).
In contrast to these patterns, prevalence of clinical depression is high in all age categories, including otherwise healthy adolescents and young adults. In one study of the US population, for example, the 12 month prevalence for a major depression episode was highest in the youngest age category (15–24 year olds). The high prevalence of depression is also an outlier when compared to the prevalence of major mental retardation, autism, and schizophrenia, all with prevalence rates about one tenth that of depression, or less.
The common occurrence and persistence of a trait like clinical depression with such negative effects early in life is difficult to explain. (Rates of infectious disease are high in young people, of course, but clinical depression is not thought to be caused by an infection.) Evolutionary psychology and its application in evolutionary medicine suggest how behaviour and mental states, including seemingly harmful states such as depression, may be past adaptations to recurring reproductive problems faced by our ancestors, actually having improved however disadvantageous in the modern world, the fitness of either the individual or their relatives. It has been argued, for example, that Abraham Lincoln's life-long depression was a source of insight and strength. Some even suggest that "we aren’t designed to have happiness as our natural default" and so a state of depression is the evolutionary norm.
The following hypotheses attempt to identify a benefit of depression that outweighs its obvious costs. All take as their starting point the fact that one of the most potent, well-established causes of major depression is a severe negative life event.
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