As part of NHEHS Science Week, we invited Maria Zicos from the Queen Mary University of London and the Natural History Museum to talk about her PhD work on why some species survive and why some become extinct.

Here’s what some of our Year 9 students took from the fascinating talk:

Matilda L

“Today, the 18th of March 2022. Year 9 had a talk from Maria Zicos, who is studying at the Queen Mary University and the Natural history Museum, to achieve her PhD. Her talk centred around the development of a species over time, how they are affected by their environment and why some species survive and others become extinct.  To do this she is studying ancient sloths, specifically the group of Darwin’s Ground Sloths in the Cueva del Milodón Cave, that became extinct 11,000 years ago after beginning to live there 17,00 years ago. 

To achieve this, she extracted mitochondrial DNA from ancient sloth skins using ancient DNA methods to achieve optimum information out of each specimen. Out of this, she was able to pattern 4 lines of DNA code, that were studied for patterns and turned into graphs to study. From this she was able to determine two scenarios leading to the extinction of the specific species, one family of females lived at the cave for the duration of their existence, hence why all the mitochondrial information passed from mother to child was the same or a small group of sloths broke apart from the rest of the population and became isolated at the cave only mating and living among themselves. 

These conclusions show that the group of Darwin’s ground sloths living in the cave did not vary much over time, meaning that they were unable to change with their environment, leading to their extinction. This information can be used to help conserve and save modern species today and can give us a helpful insight into the evolution of a species over time. Overall I found this talk interesting and insightful.”

Yuna T

“On the 18th of March, we had a talk from Maria Zicos about sloths and their history. Ancient sloths could grow to be as large as an elephant. They roamed North America and became extinct around 10,000 years ago. Sloths have an average life span of 20 to 30 years in the wild, but captive sloths tend to live a bit longer. From that time, they spread all around America and they varied in sizes and in different personalities. We learnt that sloths developed from different species and many interesting facts. Other than learning about the history of animals, we also learnt that You can learn a lot about animals from researching their past and that anything can spark someone’s interest.”

Bronwyn O

“On 18th March 2022 we had a presentation from Maria Zicos (PhD) from Queen Mary’s University and the Natural History Museum. She is questioning why some animals have gone extinct over the last 2 million years and some aren’t. She was investigating this by studying DNA with ancient DNA methods involving lots of cleaning and care to avoid contamination. She had a focus on sloths, originated from South America however they have inhabited all over the Americas. Sloths have come in a variety of sizes over the years, sometimes reaching as tall as giraffes and as heavy as elephants, with an accompanying variety of diets. She had a specific interest in the past of Darwins ground sloth originating from Chile, Cueva del Milodón  She studied the ancient DNA of 2000 years of sloths and found little differences between their DNA indicating few related sloths moved into the cave together or one family had lived in the cave. However DNA had only been discovered 70 years ago giving us little information on the genetic past of animals. She had also been studying a group of mammals known as solenodons, their modern day relatives including hedgehogs, shrews and moles. Specifically the Hispaniolan solenodon which are evolutionarily rare due to their venomous nature and currently endangered. She is working to answer how they are doing, how separate are they and how much conservation work is needed to keep them extant.”

A big thank you to Maria for such an informative talk.