From the slime coating slugs to the saliva in our mouths, many slippery bodily fluids contain mucus. So how did this marvel of biology evolve?
Evolution
Aug 26, 2022
0
171
A new study of the genetic history of Sardinia, a Mediterranean island off the western coast of Italy, tells how genetic ancestry on the island was relatively stable through the end of the Bronze Age, even as mainland Europe ...
Biotechnology
Feb 24, 2020
0
3117
To determine where a sound is coming from, animal brains analyze the minute difference in time it takes a sound to reach each ear—a cue known as interaural time difference. What happens to the cue once the signals get to ...
Plants & Animals
Mar 18, 2019
0
480
The largest study to date of ancient DNA from the Iberian Peninsula (modern-day Portugal and Spain) offers new insights into the populations that lived in this region over the last 8,000 years. The most startling discovery ...
Archaeology
Mar 14, 2019
2
1035
A study of hundreds of new genomes from across the globe has yielded insights into modern genetic diversity and ancient population dynamics, including compelling evidence that essentially all non-Africans today descend from ...
Archaeology
Sep 21, 2016
15
3546
(Phys.org)—Human genomic diversity studies provide a window to population movements across regions and societies throughout history. Generally, South America has been underrepresented in such studies, but recognizing that ...
The setting: Europe, about 7,500 years ago. Agriculture was sweeping in from the Near East, bringing early farmers into contact with hunter-gatherers who had already been living in Europe for tens of thousands of years.
Archaeology
Sep 17, 2014
10
5
(Phys.org) —Southern Europeans are more genetically diverse than Northern Europeans. Geneticists have several different explanations for this phenomenon, one of which is migration from Africa to southern Europe. However, ...
(Phys.org) —A new study conducted by a team of American and Greek researchers has found that the people of the ancient Minoan civilization living on the island of Crete most likely came from Europe. In their paper published ...
New research raises questions about the theory that modern humans and Neanderthals at some point interbred, known as hybridisation. The findings of a study by researchers at the University of Cambridge suggests that common ...
Archaeology
Aug 13, 2012
20
2
An ancestor is a parent or (recursively) the parent of an ancestor (i.e., a grandparent, great-grandparent, great-great-grandparent, and so forth).
Two individuals have a genetic relationship if one is the ancestor of the other, or if they share a common ancestor. In evolutionary theory, species which share an evolutionary ancestor are said to be of common descent. However, this concept of ancestry does not apply to some bacteria and other organisms capable of horizontal gene transfer.
Assuming that all of an individual's ancestors are otherwise unrelated to each other, that individual has 2n ancestors in the nth generation before him and a total of about 2g+1 ancestors in the g generations before him. In practice, however, it is clear that the vast majority of ancestors of humans (and indeed any other species) are multiply related (see Pedigree collapse). Consider n = 40: the human species is more than 40 generations old, yet the number 240, approximately 1012 or one trillion, dwarfs the number of humans that have ever lived.
Ignoring the possibility of other inter-relationships (even distant ones) among ancestors, an individual has a total of 2046 ancestors up to the 10th generation, 1024 of which are 10th generation ancestors. With the same assumption, any given person has over a billion 30th generation ancestors (who lived roughly 1000 years ago) and this theoretical number increases past the estimated total population of the world in around AD 1000. (All of these ancestors will have contributed to one's autosomal DNA is concerned: this excludes Y-chromosomal DNA and mitochondrial DNA.)
Some cultures confer reverence to ancestors, both living and dead; in contrast, some more youth-oriented cultural contexts display less veneration of elders. In other cultural contexts, some people seek providence from their deceased ancestors; this practice is sometimes known as ancestor worship or, more accurately, ancestor veneration.
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