Science | OpenSTEM Pty Ltd

The Science of Cats

Ah, the comfortable cat! Most people agree that cats are experts at being comfortable and getting the best out of life, with the assistance of their human friends – but how did this come about? Geneticists and historians are continuing to study how cats and people came to live together and how cats came to organise themselves into such a good deal in their relationship with humans. Cats are often allowed liberties that few other animals, even domestic animals, can get away with – they are fed and usually pampered with comfortable beds (including human furniture), are kept warm, cuddled on demand; and, very often, are not even asked to provide anything except affection (on their terms!) in return. Often thought of as solitary animals, cats’ social behaviour is actually a lot more complex and recently further insights have been gained about how cats and humans came to enjoy the relationship that they have today.

Many people know that the Ancient Egyptians came to certain agreements with cats – cats are depicted in some of their art and mummified cats have been found. It is believed that cats may have been worshipped as representatives of the Cat Goddess, Bastet – interestingly enough, a goddess of war! Statues of cats from Ancient Egypt emphasise their regal bearing and tendency towards supercilious expressions. Cats were present in Egyptian art by 1950 B.C. and it was long thought that Egyptians were the first to domesticate the cat. However, in 2004 a cat was found buried with a human on the island of Cyprus in the Mediterranean 9,500 years ago, making it the earliest known cat associated with humans. This date was many thousands of years earlier than Egyptian cats. In 2008 a site in the Nile Valley was found which contained the remains of 6 cats – a male, a female and 4 kittens, which seemed to have been cared for by people about 6,000 years ago.

African Wild Cat, photo by Sonelle, CC-BY-SA

It is now fairly well accepted that cats domesticated people, rather than the other way round! Papers refer to cats as having “self-domesticated”, which sounds in line with cat behaviour. Genetically all modern cats are related to African (also called Near Eastern) wild cats 8,000 years ago. There was an attempt to domesticate leopard cats about 7,500 years ago in China, but none of these animals contributed to the genetic material of the world’s modern cat populations. As humans in the Near East developed agriculture and started to live in settled villages, after 10,000 years ago, cats were attracted to these ready sources of food and more. The steady supply of food from agriculture allowed people to live in permanent villages. Unfortunately, these villages, stocked with food, also attracted other animals, such as rats and mice, not as welcome and potential carriers of disease. The rats and mice were a source of food for the cats who probably arrived in the villages as independent, nocturnal hunters, rather than as deliberately being encouraged by people.

Once cats were living in close proximity to people, trust developed and soon cats were helping humans in the hunt, as is shown in this detail from an Egyptian tomb painting on the right. Over time, cats became pets and part of the family and followed farmers from Turkey across into Europe, as well as being painted sitting under dining tables in Egypt. People started to interfere with the breeding of cats and it is now thought that the Egyptians selected more social, rather than more territorial cats. Contrary to the popular belief that cats are innately solitary, in fact African Wild Cats have complex social behaviour, much of which has been inherited by the domestic cat. African wild cats live in loosely affiliated groups made up mostly of female cats who raise kittens together. There are some males associated with the group, but they tend to visit infrequently and have a larger range, visiting several of the groups of females and kittens. The female cats take turns at nursing, looking after the kittens and hunting. The adult females share food only with their own kittens and not with the other adults. Cats recognise who belongs to their group and who doesn’t and tend to be aggressive to those outside the group. Younger cats are more tolerant of strangers, until they form their own groups. Males are not usually social towards each other, but occasionally tolerate each other in loose ‘brotherhoods’.

In our homes we form the social group, which may include one or more cats. If there is more than one cat these may subdivide themselves into cliques or factions. Pairs of cats raised together often remain closely bonded and affectionate for life. Other cats (especially males) may isolate themselves from the group and do not want to interact with other cats. Cats that are happy on their own do not need other cats for company. It is more common to find stressed cats in multi-cat households. Cats will tolerate other cats best if they are introduced when young. After 2 years of age cats are less tolerant of newcomers to the group. Humans take the place of parents in their cats’ lives. Cats who grow up with humans retain some psychological traits from kittenhood and never achieve full psychological maturity.

At the time that humans were learning to manipulate the environment to their own advantage by domesticating plants and animals, cats started learning to manipulate us. They have now managed to achieve very comfortable and prosperous lives with humans and have followed humans around the planet. Cats arrived in Australia with the First Fleet, having found a very comfortable niche on sailing ships helping to control vermin. Matthew Flinders‘ cat, Trim, became famous as a result of the book Flinders wrote about him. However, cats have had a devastating effect on the native wildlife of Australia. They kill millions of native animals every year, possibly even millions each night. It is thought that they have been responsible for the extinction of numbers of native mice and small marsupial species. Cats are very efficient and deadly nocturnal hunters. It is recommended that all cats are kept restrained indoors or in runs, especially at night. We must not forget that our cuddly companions are still carnivorous predators.

Am I a Neanderthal?

The whole question of how Neanderthals are related to us (modern humans) has been controversial ever since the first Neanderthal bones were found in Germany in the 19th century. Belonging to an elderly, arthritic individual (a good example of how well Neanderthals cared for each other in social groups), the bones were reconstructed to show a stooping individual, with a more ape-like gait, leading to Neanderthals being described as the “Missing Link” between apes and humans, and given the epithet “ape-man”.

Who were the Neanderthals?

Modern reconstruction – Smithsonian Museum of Natural History

Neanderthals lived in the lands surrounding the Mediterranean Sea, and as far east as the Altai Mountains in Central Asia, between about 250,000 and about 30,000 years ago. They were a form of ancient human with certain physical characteristics – many of which probably helped them cope with the cold of Ice Ages. Neanderthals evolved out of an earlier ancestor – Homo erectus, possibly through another species – Homo heidelbergensis. They had a larger brain than modern humans, but it was shaped slightly differently, with less development in the prefrontal cortex, which allows critical thinking and problem-solving, and larger development at the back of the skull, and in areas associated with memory in our brains. It is possible that Neanderthals had excellent memory, but poor analytical skills. They were probably not good at innovation – a skill which became vital as the Ice Age ended and the global climate warmed, sea levels rose and plant and animal habitats changed.

Neanderthals were stockier than modern humans, with shorter arms and legs, and probably stronger and all-round tougher. They had a larger rib cage, and probably bigger lungs, a bigger nose, larger eyes and little to no chin. Most of these adaptations would have helped them in Ice Age Europe and Asia – a more compact body stayed warmer more easily and was tough enough to cope with a harsh environment. Large lungs helped oxygenate the blood and there is evidence that they had more blood supply to the face – so probably had warm, ruddy cheeks. The large nose warmed up the air they breathed, before it reached their lungs, reducing the likelihood of contracting pneumonia. Neanderthals are known to have had the same range of hair colours as modern humans and fair skin, red hair and freckles may have been more common.

They made stone tools, especially those of the type called Mousterian, constructed simple dwellings and boats, made and used fire, including for cooking their food, and looked after each other in social groups. Evidence of skeletons with extensive injuries occurring well before death, shows that these individuals must have been cared for, not only whilst recovering from their injuries, but also afterwards, when they would probably not have been able to obtain food themselves. Whether or not Neanderthals intentionally buried their dead is an area of hot controversy. It was once thought that they buried their dead with flowers in the grave, but the pollen was found to have been introduced accidentally. However, claims of intentional burial are still debated from other sites.

What Happened to the Neanderthals?

Anatomically modern humans emerged from Africa about 100,000 years ago. Recent studies of human genetics suggests that modern humans had many episodes of mixing with various lineages of human ancestors around the planet. Modern humans moved into Asia and Europe during the Ice Age, expanding further as the Ice Age ended. Modern humans overlapped with Neanderthals for about 60,000 years, before the Neanderthals disappeared. It is thought that a combination of factors led to the decline of Neanderthals. Firstly, the arrival of modern humans, followed by the end of the Ice Age, brought about a series of challenges which Neanderthals might have been unable to adapt to, as quickly as necessary. Modern humans have more problem solving and innovation capability, which might have meant that they were able to out-compete Neanderthals in a changing environment. The longest held theory is that out ancestors wiped out the Neanderthals in the first genocide in (pre)history. A find of Neanderthals in a group, across a range of ages, some from the same family group, who all died at the same time, is one of the sites, which might support this theory, although we don’t actually know who (or what) killed the group. Cut marks on their bones show that they were killed by something using stone tools. Finally, there is more and more evidence of what are called “transitional specimens”. These are individuals who have physical characteristics of both groups, and must represent inter-breeding. An example is the 4 year old child from the site of Abrigo do Lagar Velho in Portugal, which seems to have a combination of modern and Neanderthal features. The discovery of Neanderthals genes in many modern people living today is also proof that we must have interbred with Neanderthals in the past. It is thought that the genes were mixed several times, in several parts of the world.

Am I a Neanderthal?

So how do we know if we have Neanderthals genes? Neanderthal genes have some physical characteristics, but also other attributes that we can’t see. In terms of physical characteristics, Neanderthal aspects to the skull include brow ridges (ridges of bone above the eyes, under the eyebrows); a bump on the back of the head – called an occipital chignon, or bun, because it looks like a ‘bun’ hairstyle, built into the bone; a long skull (like Captain Jean-Lu Picard from Star Trek – actor Patrick Stewart); a small, or non-existent chin; a large nose; a large jaw with lots of space for wisdom teeth; wide fingers and thumbs; thick, straight hair; large eyes; red hair, fair skin and freckles! The last may seem a little surprising, but it appears that the genes for these characteristics came from Neanderthals – who had a wide range of hair colours, fair skin and, occasionally, freckles. Increased blood flow to the face also would have given Neanderthals lovely rosy cheeks!

Less obvious characteristics include resistance to certain diseases – parts of our immune systems, especially with reference to European and Asian diseases; less positively, an increased risk of other diseases, such as type 2 diabetes. Certain genes linked to depression are present, but ‘switched off’ in Neanderthals. The way that these genes link to depression, and their role in the lifestyles of early people (where they may have had benefits that are no longer relevant) are future topics for research and may help us understand more about ourselves.

Neanderthals genes are present in modern populations from Europe, Asia, Northern Africa, Australia and Oceania. So, depending on which parts of the world our ancestry is from, we may have up to 4% of our genetics from long-dead Neanderthal ancestors!

Oceanography and the Continents

Marie Tharp (30 July, 1920 – 23 August, 2006) was an oceanographer and cartographer who mapped the oceans of the world. She worked with Bruce Heezen, who collected data on a ship, mapping the ocean floor.

Tharp turned the data into detailed maps. At that time women were not allowed to work on research ships, as it was thought that they would bring bad luck! However, Tharp was a skilled cartographer, and as she made her maps of the floor of the oceans of the world, with their ridges and valleys, she realised that there were deep valleys which showed the boundaries of continental plates. She noticed that these valleys were also places with lots of earthquakes and she became convinced of the basics of plate tectonics and continental drift.

Between 1959 and 1963, Tharp was not mentioned in any of the scientific papers published by Heezen, and he dismissed her theories disparagingly as “girl talk”. As this video from National Geographic shows, she stuck to her guns and was vindicated by the evidence, eventually managing to persuade Heezen, and the scientific community at large, of the validity of the theories. In 1977, Heezen and Tharp published a map of the entire ocean floor. Tharp obtained degrees in English, Music, Geology and Mathematics during the course of her life. In 2001, a few weeks before her 81st birthday, Marie Tharp was awarded the Lamont-Doherty Heritage Award at Columbia University, in the USA, as a pioneer of oceanography. She died of cancer in 2006.

The National Geographic video provides an excellent testimony to this woman pioneer in oceanography.

Mildred Dresselhaus, the Queen of Carbon | NY Times

“Dr. Dresselhaus, who helped transform carbon into the superstar of modern materials science, was renowned for her efforts to promote the cause of women in science.”

Millie Dresselhaus (nee Spiewak) high school yearbook 1948 — 1948 A tribute at Hunter High School.

“Mildred (Millie) Dresselhaus, a professor emerita at the Massachusetts Institute of Technology whose research into the fundamental properties of carbon helped transform it into the superstar of modern materials science and the nanotechnology industry, died on Monday in Cambridge, Mass. She was 86.”

New Research on Our Little Cousins to the North!

Last year, several research papers were published on the ongoing excavations and analysis of material from the island of Flores in Indonesia, where evidence of very small stature hominins was found in the cave of Liang Bua, in 2003. The initial dates dated these little people to between 50,000 and about 14,000 years ago, which would have meant that they lived side-by-side with anatomically modern humans in Indonesia, in the late Ice Age. The hominins, dubbed Homo floresiensis, after the island on which they were found, stood about 1m tall – smaller than any group of modern humans known. Their tiny size included a tiny brain – more in the range of 4 million year old Australopithecus than anything else. However, critical areas of higher order thinking in their brains were on par with modern humans.

Baffled by the seeming wealth of contradictions, these little people raised, researchers returned to the island, and the cave of Liang Bua, determined to check all of their findings in even more detail. Last year, they reported that they had in fact made some mistakes, the first time around. Very, very subtle changes in the sediments of the deposits, revealed that the Homo floresiensis bones belonged to some remnant older deposits, which had been eroded away in other parts of the cave, and replaced by much younger layers. Despite the samples for dating having been taken from close to the hominin bones, as luck would have it, they were all in the younger deposits! New dates, run on the actual sediments containing the bones, gave ages of between 190,000 to 60,000 years. Dates from close to the stone tools found with the hominins gave dates down to 50,000 years ago, but no later.

The researchers – demonstrating a high level of ethics and absolutely correct scientific procedure, published the amended stratigraphy and dates, showing how the errors had occurred. At another site, Mata Menge, they had also found some ancestral hominins – very similar in body type to the ones from Liang Bua, dated to 700,000 years ago. Palaeoanthropologists were able to find similarities linking these hominins to the early Homo erectus found on Java and dated to about 1.2 million years ago, leading researchers to suggest that Homo floresiensis was a parallel evolution to modern humans, out of early Homo erectus in Indonesia, making them a fairly distant cousin on the grand family tree.

Careful examination of the deposits has now also called in to question whether Homo floresiensis could control fire. We know that they made stone tools – of a type pretty much unchanged over more than 600,000 years, and they used these tools to help them hunt Stegodon – an Ice Age dwarf elephant, which was as small as 1.5m at the shoulder. However, researchers now think that evidence of controlled fire is only in layers associated with modern humans. It is this cross-over between Homo floresiensis and modern humans, arriving about 60,000 – 50,000 years ago, that is a focus of current research – including that of teams working there now. At the moment, it looks as if Homo floresiensis disappears at about the same time that modern humans arrive, which sadly, is a not totally unlikely pattern.

What does this have to do with Australia? Well, it’s always interesting to get information about our immediate neighbours and their history (and prehistory). But beyond that – we know that the ancestors of Aboriginal people (modern humans) were in Australia by about 60,000 – 50,000 years ago, so understanding how they arrived is part of understanding our own story. For more case studies on interesting topics in archaeology and palaeontology see our Archaeology Textbook resources for Year 11 students.

Getting to know Homo erectus

Homo erectus, Museum of Natural History, Ann Arbor, Michigan (photo: Thomas Roche)

Homo erectus was an ancient human ancestor that lived between 2 million and 100,000 to 50,000 years ago. It had a larger body and bigger brain than most earlier human ancestors. Although recent debates revolve around how we classify these fossils, and whether they should be broken down into lots of smaller sub-groups, it is generally agreed that Australopithecines in Africa pre-dated the advent of the Homo lineage. Predecessors to Homo erectus, include Homo habilis (“handy man”), a much smaller specimen.

Compared with modern Homo sapiens, which have only been around for the last 200,000 years, Homo erectus, or “upright man,” was very “successful” in a biological sense and lived on the Earth for 10 – 20 times longer than modern humans have been around.

Fossils of H. erectus show that it was the first human ancestor to live outside of Africa – one of the first fossils found was unearthed in the 19th century in Indonesia – others have been found across Asia, including China, as well as Europe and Africa.

A recent interesting summary of information about Homo erectus can be read at http://www.livescience.com/41048-facts-about-homo-erectus.html. OpenSTEM also has a PDF resource on Homo erectus (part of our Archaeology Textbook for Senior Secondary).

Get Hands-On!

If you’re in the greater Brisbane area and would like to have your students touch, compare and otherwise explore human ancestor skulls – talk to us! OpenSTEM has a growing range of 3D printed fossil skulls and our resident archaeologist Dr Claire is available for workshops at primary and high school level (such as Introduction to Archaeology and Fossils).