Scientists find research gold in Brac caves

The Brac cave scientists, from left, Mike Buckley, Andrew Chamberlain, Phil Manning, Victoria Egerton, Bill Sellers and their Cayman Brac nature guide Thomas ‘TJ’ Sevik, back center. Not pictured is Virginia Harvey, lead author of the team’s recently published article.

The caves in Cayman Brac may or may not have once been used by pirates to hide their loot, but today the caves are an underground treasure trove for scientists studying the impact of climate change and humans on the evolution of species.

A team of scientists from the University of Manchester and the College of Charleston (South Carolina) recently published an article describing the findings of what they hope will be just the first of several scientific projects the team will conduct in the caves of Cayman Brac.

“I was utterly gobsmacked at how good the fossil record is in these caves because in tropical climates, things don’t usually preserve,” Phil Manning said of his first field trips to the caves a few years ago.

“I don’t need to come to Cayman to get a suntan,” he said. “I want to come to Cayman to crawl through caves in the dark.”

Mr. Manning, a professor of paleontology at the College of Charleston, said a cave system such as the one in Cayman Brac is “akin to having a time machine.”

“We can see in the caves what life was like on the island before humans and also how humans have impacted life,” Mr. Manning said. “It’s a wonderful opportunity to measure what happened to endemic species.”

The team’s first project on the Brac involved testing a technique to determine if a bone specimen is suitable for radiocarbon analysis – or carbon dating – which is a way of determining the age of archaeological artifacts of biological origin.

Carbon dating requires the presence of collagen, the main protein in bones, and is preserved in fossils. Sometimes, however, collagen has deteriorated, making an otherwise well-preserved specimen unsuitable for carbon dating. Tropical climates, in particular, have a poor survival record for animal remains because of the high temperatures and humidity that can affect collagen survival.

Since carbon dating is an expensive technique, scientists are interested in determining whether a specimen is suitable for the testing, to cut down on the number of failed dating attempts.

Cayman Brac nature guide Thomas ‘TJ’ Sevik, was instrumental in guiding the scientists through the caves. - Photo: Phil Manning
In Cayman Brac, the scientists found that collagen fingerprinting was a successful method of categorizing whether samples are suitable for dating. – Photo: Phil Manning

The technique the scientists in the Brac used to determine whether a sample would be suitable for carbon dating is called “ZooMS” or “collagen fingerprinting.”

It was first developed by team member Mike Buckley as a means to identify species of animals from tiny bone fragments. Mr. Buckley said that while DNA testing is often used to identify species, the DNA samples of the materials he works with are often too degraded to test, either because the material is too old or because of the climate.

With collagen fingerprinting, scientists extract a sample of collagen from a fossil and identify a “fingerprint” comprised of the unique chemical markers in the chains of amino acids that exist in the collagen.

Mr. Buckley and another team of scientists used collagen fingerprinting to identify a 3.5 million-year-old specimen as the first evidence of an extinct giant camel in the high Arctic.

In Cayman Brac, the scientists found that collagen fingerprinting was a successful method of categorizing whether samples are suitable for dating.

The method was tested on “sub-fossil bone specimens” from the Brac caves, several of which were remains of a now-extinct species of hutia, a large rodent.

According to the scientists’ recently published article, “Collagen Fingerprinting: A New Screening Technique for Radiocarbon Dating Ancient Bone,” all of the bone samples that yielded radiocarbon dates generated excellent collagen fingerprints, and conversely those that gave poor fingerprints also failed dating.

Mr. Buckley said his research is primarily about biodiversity change through time and the effect that humans have had on the native fauna, and how quickly extinctions occurred.

“Cayman Brac is a great place to do this kind of research because it’s relatively pristine. It’s really untouched when it comes to more recent developments, so we’ve got quite a good geological archive,” Mr. Buckley said.

Mr. Manning said they have discovered several extinct animals in the caves. He also said that some of the dates are so young on some of the bones that it could be possible that some of those animals thought to be extinct are not, and “that’s a huge deal.”

“I am absolutely positive that the Cayman caves can tell us something about the climate, its impact on species, and the impact of humans on the evolution of species,” Mr. Manning said. “If you think of biodiversity hot spots on the planet, you’re living in one. You’re living in one of the most precious ecosystems that exists on the planet.”

He said he hopes there will be additional research projects conducted in Cayman Brac, but that the researchers are desperately in need of funding in order to conduct future studies.