Humans reach southern South America

DNA from 139 Indigenous groups reveal that humans reached southern South America by 14,500 years ago.

A new genetic analysis reveals that humans crossing from Asia along the Bering Land Bridge during the last ice age underwent three major population splits as they traveled through the Americas. This journey has been identified as the longest human migration out of Africa. Eventually, a group settled in the southern part of South America some 14,500 years ago.

An international team of scientists analyzed 1,537 genomes of people from 139 different ethnic groups to identify genetic characteristics of the earliest Americans.

The GenomeAsia 100K consortium collected the genetic material, including some from Asian populations whose ancestors made early migrations into the Americas. The scientists were able to identify the genetic background of indigenous people throughout the Americas. They pinpointed three key time periods when the long-distance travelers split up.

The first population split occurred between 26,800 and 19,300 years ago during the Last Glacial Maximum. This was when Indigenous Americans split from North Eurasian people. These dates are consistent with a Native American presence at White Sands in New Mexico, as evidenced by ancient footprints and vehicle drag marks dated to 23,000 to 21,000 years ago.

The next major population split happened between 17,500 and 14,600 years ago. The indigenous population in North America split, and some made their way south. This Mesoamerican group then split rapidly into four native genetic lineages around 13,900 years ago. These groups were ancestral Pueblo peoples in the southwest US, as well as Amazonians, Andeans and Patagonians in South America.

This estimation actually fits well with the archaeological records, which indicate that people were living in the furthest southern reaches of the South American continent by about 14,500 years ago.

As people made their way into the new land tens of thousands of years ago, they experienced a reduction in their genetic diversity. First it was because of geographic barriers. Later, the populations were decimated after the arrival of European colonists.

One key loss was in the variation in human leukocyte antigen (HLA) genes. A high diversity of HLA genes is important for immune system health. In regions such as Southeast Asia with a high number of disease-causing organisms, previous studies found a high diversity of HLA genes. But in the Indigenous South American genomes, there was significantly lower diversity in the HLA genes. This may have led to these people being more vulnerable to novel pathogens.

One of the researchers’ aims is to emphasize the special medical needs of contemporary Indigenous peoples. Some have gene variants associated with problems like adverse drug reactions.

 

https://www.msn.com/en-us/news/world/humans-reached-southern-south-america-by-14-500-years-ago-genomes-from-139-indigenous-groups-reveal/ar-AA1ER86r?ocid=hpmsn&cvid=e2137095d6244d2d9b66aa91eafcef03&ei=65

What Was the Earth Like?

We’ve examined some of the creatures that existed before the dinosaurs, but what was the Earth like way back then?

From 354 to 290 million years ago was the Carboniferous Period. Hot and humid conditions covered the northern landmass, while the southern lands were much colder. Large club mosses, tree ferns, and horsetails grew in swamps and estuaries, along with seed-bearing plants. Some plants were up to 100 feet tall.

The insect population was quite varied, with millipedes, dragonflies, and other bugs. Some flying insects had wingspans up to two feet wide! Around the middle of the period, reptiles evolved as the first land-dwelling animals, and sharks and bony fishes replaced the jawless agnathans and armored placodems in the seas. Starfish, gastropods, sea urchins, and other marine invertebrates flourished on the reefs.

Approximately 350 million years ago, coal forests began to form in wetlands at the edges of continents. The submerged plant matter did not decompose completely and ended up being buried. This eventually transformed into coal.

The early reptiles had similar skeletal features to those of amphibians, but there were differences in their skulls and vertebrae that signified their relationship to later reptiles such as turtles and dinosaurs.

Then came glaciations, a decrease in sea levels, and the formation of Pangaea, when the continents joined together. A minor extinction event of both marine and land life happened at the end of the period due to climate change. This is known as the Carboniferous rainforest collapse.

 

https://www.msn.com/en-us/news/technology/9-massive-prehistoric-animals-that-lived-before-dinosaurs/ar-BB1pX9NZ?ocid=mailsignout&pc=U591&cvid=4b29427ca0eb40e9a777238542e8cbdc&ei=39