Often considered the world's oddest mammal, Australia's beaver-like, duck-billed platypus exhibits an array of bizarre characteristics: it lays eggs instead of giving birth to live babies, sweats milk, has venomous spurs ...
Plants & Animals
Jan 06, 2021
15
2980
Tropical Asia and Africa are the only regions on Earth that retain diverse populations of large, land-dwelling mammals, such as elephants, rhinos, and big cats. A new study co-authored by Yale researcher Advait M. Jukar suggests ...
Paleontology & Fossils
Dec 09, 2020
3
47
A trio of researchers, two with the University of Cape Town, the other the University of the Witwatersrand has found evidence that suggests wetland-dwelling lithornithids from the Cretaceous, likely used remote touch to find ...
A small team of researchers from France, Italy and the U.S., has found evidence that suggests Sahelanthropus tchadensis was not a hominin, and thus was not the earliest known human ancestor. In their paper published in Journal ...
Many human traits, such as height and disease susceptibility, depend on genes that are encoded in our DNA. These genes are switched on and off and further fine-tuned by important but hard-to-find regions in the genome.
Evolution
Nov 16, 2020
0
6
For hundreds of thousands of years, early humans in the East African Rift Valley could expect certain things of their environment. Freshwater lakes in the region ensured a reliable source of water, and large grazing herbivores ...
Archaeology
Oct 21, 2020
4
403
A team of researchers, led by the University of Bristol, has revealed our most ancient ancestors were ecologically diverse, despite lacking jaws and paired fins.
Plants & Animals
Oct 01, 2020
0
248
New species of microbial life are continually being identified, but localizing them on a phylogenetic tree is a challenge. Now, researchers at the University of Tsukuba have pinpointed barthelonids, a genus of free-living ...
Evolution
Sep 23, 2020
0
83
One of the reasons humans are so resilient is our ability to mold our behavior to ever changing situations. It wasn't so long ago that many of us hugged when we met. In the middle of a pandemic, in which close contact between ...
Evolution
Sep 18, 2020
0
32
For most vertebrates, losing a limb is permanent, but a lucky few species—such as salamanders and tadpoles—have the ability to completely regrow complex body parts. Understanding the molecular mechanisms underlying this ...
Evolution
Sep 16, 2020
0
335
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 surely 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.
This text uses material from Wikipedia, licensed under CC BY-SA
