Category Archives: Mac’s Notebook

Neanderthals, Our Species’ Closest Cousins.

An Artist’s Reconstruction of a Neanderthal

Humans may not have lived with dinosaurs, but they did once share the Earth with creatures very similar to us. Neanderthals, or homo neanderthalensis, shared the planet with us until about 40,000 years ago. Despite them having died out millennia ago, archaeologists are still finding evidence of their existence, and learning more about what their lives were like, and how they related to us. Some things that we do know are that they were very similar to us intellectually, with practices such as wearing clothes and having burial rites, and that they coexisted with us for some time.

One of the biggest questions about Neanderthals is whether or not they were a distinct species, or if they were just a subspecies of humanity. The current view of the scientific community is that they are a distinct species, and that they and humans both evolved from homo erectus, an ancestor that existed in Africa hundreds of thousands of years ago. This conclusion was largely reached by analyzing Neanderthal DNA and comparing it to Human DNA.

Fragments of Neanderthal 1, the First Neanderthal Fossil

Of course, that raises the question of how exactly we have intact DNA from a species that went extinct 40,000 years before we even knew DNA was a thing. The answer is that tiny amounts of DNA can persist in the core of fossilized bone, and thankfully we’ve found a substantial number of fossils from Neanderthals. The first to be discovered wasn’t immediately recognized as being from a distinct species — after all, it was the first evidence we had of there being another hominid species in our planet’s history — but analysis of the structure of its skull found it to be so distinct from modern humans that it had to be a different species.

A Neanderthal’s Upper Jaw

Since then, we’ve found out more and more about Neanderthals. Discoveries such as the Altamura Skeleton, an almost complete ancient human skeleton found in Italy, have increased our understanding of exactly what they looked like. The upper jaw of a Neanderthal recently discovered in Spain revealed that Neanderthals used the gum of a poplar tree as sort of an ancient Aspirin when their stomachs hurt, and may have known about penicillin.

Find out more about Neanderthals’ dietary habits!

TRAPPIST-1, an Earth-like Solar System

An Artist’s Interpretation of the TRAPPIST-1 sytem

Astronomers recently made a discovery of colossal importance – the existence of a star system, named TRAPPIST-1, with the conditions to potentially support human life. The system has seven planets, all orbiting a red dwarf star. While the planets are about the same size as Earth, the star itself is tiny, as the term dwarf star might suggest. It’s about 1/12 the size of our sun, according to Dr. Gillion, a NASA scientist, if our sun were a basketball, this star would be a golf ball.

A Poster Made by NASA to Publicize the Discovery.

The significance of this discovery comes from the distance of the planets and the heat of the star. Astronomers currently believe that some of the planets might be in what is known as the “Goldilocks zone,” the band around a star where the temperature of a planet is low enough for water to not evaporate, but warm enough that it doesn’t free, allowing for the possibility of liquid water, which means that it could likely support life, either extraterrestrial, or that of human colonists.

The big issue however, is that the system is 39 light years away, or 235,000,000,000,000 miles away. With our current technology, this makes travel to TRAPPIST-1 completely infeasible. However, on a galactic scale, the solar system is incredibly close to Earth, only about ten times the distance of the closest star, Alpha Centauri. This gives us a huge step towards finding out more about life on other worlds, since we can observe the planets of TRAPPIST-1 much more easily than we can further worlds.

An image captured by a NASA telescope of star Trappist-1

Despite its relative proximity, we still can’t directly observe the exoplanets of TRAPPIST-1. Instead, we rely on observing the star at the center of the system, and looking for fluctuations in the light it puts out to detect planets. Likewise, to make observations about the atmosphere and conditions of the planets, we have to use indirect methods. For example, to determine the status of the atmosphere on a planet, scientists look at the infrared radiation being emitted, since it’s possible to derive a lot of information about the temperature of a planet from the heat it admits into space.

The Mantle of the Earth Now Believed to be Hotter Than Before.

A visualization of the layers of the Earth

The mantle of the Earth. The 1800 mile thick section of the Earth’s interior between the crust, which we live on, and the core, the ball of molten metal at the center of the planet. Compared to the other two sections, its makeup is more variable, with sections closer to the core being made up of solid rock, and upper sections reaching their melting temperatures and becoming molten. The mantle is responsible for much of the interesting geological occurrences on the planet, the most impressive of which is likely volcanic eruptions, which occur when molten mantle rock is shoved upwards and reaches the crust.

Molten rock from the mantle causes volcanic eruptions

Of course, volcanoes are only possible if the rock of the mantle is molten, which requires very high temperatures. This makes the question of the temperature of the Earth’s mantle one that scientists are very interested in solving. Scientists already know certain things about the Earth’s mantle, most importantly that there’s a boundary a couple dozen miles below the surface of the Earth that marks the point above which the rock begins to melt. To find the temperature of mantle rock, scientists should just have to find what temperature its components melt at, and derive it from that.

A sample of peridotite

The main obstacle to this has been that the material most of the upper mantle is made of, peridotite, tends to have water within it, and it’s very difficult to control the amount of water to get it to match the Earth’s core. Previous attempts to account for this have found that the temperature of this boundary point is likely 1350° Celsius, or 2462° Fahrenheit. However, a new method to test the amount of moisture in a sample of peridotite found that previous samples weren’t dry at all, despite previous assumptions! As a result, they found that the temperature of the mantle is likely 60° above what had previously been estimated, or 1410° Celsius. While this number may seem relatively insignificant, previous changes to the temperature of the mantle had been around 10° or less, so this represents a substantial change to our understanding of what lies beneath our feet.

The Oldest Garment in the World

Archaeologists recently confirmed that the Tarkhan Dress (which has decayed to just being a shirt at this point) is between 5,100 and 5,500 years old. This dates it to near the beginning of Egyptian society. Of course, it was a shock to find a (mostly) intact garment of such an age, since normally linen is destroyed by the ravages of time fairly quickly. (Fun fact, one of the major forces contributing to clothing falling apart over long spans of time is the friction caused by particles of dust coming into contact with it.)

The Dress was originally found in an Egyptian cemetery in the early 1900’s. Its significance was largely overlooked by the academic community, until 1977, when it was sent to the Victoria and Albert Museum. The long sleeved garment was found inside-out, and had significant creasing, suggesting that it had been actually worn, likely by one of the tomb’s occupants. At the moment, the dress stops at the midriff, but evidence such as similar, slightly younger garments, and images on nearby tombstones indicate that it would originally have been floor-length.

Alice Stevenson, the author of a recent study about the dress’ age.

The Dress has long been suspected to date back to the time of Egypt’s First Dynasty, but this was recently confirmed by radiocarbon dating. Radiocarbon dating is a process that we’ve only known about for around a century. It uses the decay of a certain Carbon isotope (isotopes are a type of particle that share chemical properties with each other, but slightly differ in mass) to measure how much time has passed. Carbon-14 is the one carbon isotope that is radioactive — which doesn’t mean it’s dangerous, just that it emits energy — and by finding the amount of it in a substance, we can tell how old it is. Since we have lots of evidence from very old things, like trees, we can use those as reference points to get very accurate dates, to within a few centuries.


The Mysterious Band of Holes

The First Photograph of the Band of Holes
The First Photograph of the Band of Holes

What would the ancient Incans have needed with thousands of holes, all around three feet wide, and two to three feet deep?  This question has plagued archaeologists ever since an aerial photograph, pictured above, publicized the phenomenon in 1931. When archaeologists got there in person, they found that the holes had been constructed by people, either by creating a pile of soil and digging a hole in that, or by piling stones in a circle. While this dispelled the rumor that the holes had been created by ancient aliens, it provided absolutely no hint as to who did make them, and why.

Victor Wolfgang von Hagen, one of the archaeologists who visited the Band in person.
Victor Wolfgang von Hagen, one of the archaeologists who visited the Band in person.

One of the earliest theories was that they were in fact all empty graves, and that the bodies had been destroyed by various natural phenomena over hundreds of years, but another man named Charles Stanish, an archaeologist  working at the University of California, Los Angeles, wasn’t convinced by this explanation.

Charles Stanish
Charles Stanish

In 2015, Charles Stanish took a team down to the Band of Holes, where they created a more detailed map of the holes, numbering 6,000, and became increasingly convinced that the holes dated to the time when the Incans conquered the Chinchan people. Based off of that belief, he hypothesized that the holes were actually a way of measuring the tax a Chinchan family would have to pay to their new overlords. There is circumstantial evidence for this — Monte Sierpe, the location of the Band of Holes, lies close to an administrative center of the Incan Empire, the place where taxes would have been collected, and the Incans had used similar schemes in other locations. They have yet to find conclusive proof, but Stanish plans to return, and look for microscopic evidence that would have been left behind. For the time being, the Band of Holes remains mysterious.