The lost great apes, EU ancestors and human fetal brain organoids | Last Week in Science (14th Jan 2024)

The lost great apes

Gigantopithecus blacki
 are the largest apes known that went extinct 210,000 years ago. They would weigh 200-300 kgs and would be as tall as 3 meters or more than 9 feet.

What changed in this ape's environment that made it extinct? To answer this question, researchers studied teeth excavated from caves in China, these apes were native to China. They found that older teeth samples indicated a healthy and balanced diet being taken by G blacki but in the teeth samples which were more recent the diet seemed to be less balanced.

By dating - finding how old the teeth samples are and comparing it with how the environment would have been at that time the researchers found further clues.

Around 3.2 million years back, G blacki were living in surroundings that were covered with dense forests mixed with open grasslands. But this environment changed in to a less dense and more open grasslands at around the time the great apes went extinct. 

The researchers are looking out for more fossils because so far they could only find teeth, especially the thigh bones so that they can better understand what made these giants apes go extinct.

Reference: Why did the world’s biggest ape go extinct?

The European ancestors

When it comes to study ancestry and human migration around the globe, researchers study the genetic material that they extract from fossils of humans. In a recent study that looked at 1000 different European ancestors, the researchers found that the current day European Union has had three different waves of human migration. The earliest coming from hunter gatherers from Asia 45,000 years ago followed by farmers from Middle East, 11,000 years ago and the most recent being the animal herders that came from Western Aisa some 5,000 years ago. 

There is a mixing of these populations but there are also clear distinctions between northern and southern Europe. This was because the animal herders mostly settled in the northern part of the Europe while the farmers went to the southern and western parts.

The northern population being at high risk of diabetes and Alzheimer's while the southern population being at high risk of developing a neurological condition known as multiple sclerosis can be explained by the ancestors being different in two geographically different regions of the EU.

Multiple Sclerosis is a disease where the body's immune system starts to attack the nerves of the body. As the animal herder started to settle in the northern regions the instances of disease would have increased because of the microbes being introduced by the animals in the environment. Individuals with an overactive immune system would be at an advantage in this change in the environment. This would explain why the northern population have more individuals that have an over active immune system and increasing the chances of developing auto immune disease like Multiple Sclerosis.

The study also revealed that in certain places like in Denmark the migrants completely replaced the existing local population by killing them. I wonder if an in depth analysis might be able to reveal more about the evolution of the killer instinct of humans as we advanced towards the modern world. 

Reference: Ancient DNA reveals origins of multiple sclerosis in Europe 

Mini brains from human fetus

Brain organoids are mini brains grown in the lab that help scientists to study how the brain develops or what goes wrong in diseases where the brain is not able to develop properly.

Till now, scientists have grown brain organoids from stem cells that can be created in the lab by taking cells from adult humans. While these brain organoids do help in understanding how different brain cells form but further development and forming of connections between different brain regions cannot be studied. This is where tissue from fetus can help. But using human fetal tissue especially the brain is banned in many countries like the USA. The current research happened in the EU where there is no ban. The researchers also ensured that the mini brains were not conscious or feeling pain, an ethical concern that surrounds research around growing mini brains in the lab.

The researchers used brain tissue from 12 to 15 week old aborted fetuses. They could grow different parts of the brain in a dish by taking slices from the fetal brain. These formed balls of cells that resembled the different parts of the brain. They tested drugs for brain cancer on these mini fetal brain organoids after creating cancerous cells in them and the drugs were found to be effective. The researchers now plan to use these mini brains for screening new drugs to treat brain cancer along with better studying the development of brain.