Evolution
G.D.W. |
What is the origin of bird digits? This question has caused a lot of head-scratching and beard-stroking in evolutionary biologists. Paleontological evidence suggests that the three digits in birds develop from digit position 1, 2 and 3 (thumb, index and middle finger). Embryological evidence points towards digits 2, 3 and 4 (index, middle and ring finger). Vertebrates are ‘programmed’ to develop five digits on each limb, but there are exceptions. Such as birds, which have three. But which three?
Now, Yale researchers have investigated this issue using transcriptomic data (the set of all RNA…
G.D.W. |
In 2008, a fossil tooth and finger bone were found in a cave in Siberia. After analysis it turned out to belong to a new species of human, now known as the Denisovans. In 2010, a draft of the Neanderthal genome was released, providing indications for potential interbreeding with our ancestors. In the same year, analysis of the Denisovan genome also revealed indications for potential interbreeding.
Now, a new study, published in Science, states that these interbreeding events could have boosted the human immune system.
Modern humans, Neanderthals and Denisovans all share a common ancestor in…
vongehr |
You ever wondered why it is that we share only 50% of our genes with a sibling but 98% with chimpanzees?
Humans are a freak of nature. We are in between a so called ‘tournament species’ and a ‘pair-bonding species’. In other words: naturally very aggressive primates constantly stressed in the pressure grip of macro evolution. These and many other important issues are touched on in Robert Sapolsky's lecture on Behavioral Biology, Biology 150.
Robert’s lecture is entertaining and it is possibly the most down to earth and up to date available on the nature-or-nurture debate, on how much genes…
G.D.W. |
A new study, published in Science, analyzed regulatory elements in the vertebrate genome and found three waves of evolutionary innovation in the evolution of vertebrates. Many important evolutionary changes have their roots in changes in regulatory elements, not necessarily in the occurrence of new protein-coding genes. So, it’s not the change in genes, but rather the change in gene regulation that spurred many events in vertebrate evolution.
Through computational methods, this new study searched for DNA sequences that remained the same in species that have diverged (so-called conserved…
Can we stop the crap about "selfishness" and "altruism" when discussing animal behavior? It's absolutely ridiculous the unnatural gyrations researchers go through to try and reconcile behaviors that clearly don't fit the prevailing theories.
The present "explanation" demonstrates how the altruistic behavior of some wasps (Polistes dominulus) is actually "selfish". What kind of rubbish is this?
The point was to salvage kin selection theory (which it doesn't do), by arguing that some wasps may behave "altruistically" towards unrelated queens simply so that they may "selfishly"…
G.D.W. |
Anisogamy (see figure 1), or sexual reproduction in which two different gametes fuse to produce a new individual, leads to an inequality between female and male organisms. After all, females produce a limited supply of costly egg cells, while males produce a virtually endless supply of cheap sperm cells (this is the case in the vast majority of animals, and is known as oogamy (see figure 1), in which a large, non-motile egg cell is fertilized by a small, motile sperm cell (see figure 2)) . So, females best carefully choose the male they mate with, while males best copulate as much as possible…
Where are we humans going, as a species? If science fiction is any guide, we will genetically evolve like in X-Men, become genetically engineered as in Gattaca, or become cybernetically enhanced like General Grievous in Star Wars.
All of these may well be part of the story of our future, but I'm not holding my breath. The first of these - natural selection - is impracticably slow, and there's a plausible case to be made that natural selection has all but stopped acting on us.
Genetic engineering could engender marked changes in us, but it requires a scientific bridge between genotypes - an…
Molluscs are Marvellous! — as regular readers of “Squid-a-Day” will know.
The recent presentation there of Celebrate Squid Babies brought to mind the following, from Darwin’s notebooks:
How far grander than idea from cramped imagination … that since the time of the Silurian, he has made a long succession of vile Molluscous animals — How beneath the dignity of him, …. whom it has been declared "he said let there be light&there was light."
That has prompted some theological thoughts, but first a zoological one.
It was quite natural in the 19th …
G.D.W. |
Evolutionary psychology is a field that examines human psychological traits through evolutionary glasses. Most human psychological traits are considered adaptations, the functional products of natural or sexual selection. This is tidily summarized in a quote from Cosmides and Tooby, two of the founders of the field:
Our modern skulls house a Stone Age mind.
The field, however, is quite controversial. Proponents tend to explain every aspect of the human psyche through evolutionary adaptation, whereas opponents often express the criticism that these are ‘just-so stories’. Between these two…
Human-like features of the feet and gait were in existence almost two million years earlier than previously thought, according to recent analysis of ancient footprints in Laetoli, Tanzania.
Earlier studies suggested that the characteristics of the human foot, like the ability to push off the ground with the big toe and a fully upright bipedal gait, emerged in early Homo approximately 1.9 million years-ago but researchers now say that footprints of a human ancestor dating back 3.7 million years ago show features of the foot with more similarities to the gait of modern humans than with the type…