Reading the bones: a 43,000-year-old mystery is answering some questions and prompting researchers to ask others

James Hart, Public Affairs Specialist

Paddling down a river in the National Petroleum Reserve in Alaska in summer 2012, the weather was still chilly. University of Alaska Fairbanks wildlife biologist Pam Groves and geologist Dan Mann were looking forward to getting to camp.

It was just a couple miles from a restful night when they spotted something white along the riverbank that pumped adrenaline back through their bodies. It was Bob, and he had millennia stories to tell.

Paddling closer, they realized they had found the skull of a steppe bison (B. priscus), ancestor of the iconic American bison (B. bison), complete with jawbone and teeth. Then they found a leg. Looking up, they saw more bones sticking out of the bluff.

Bison jawbone partially buried in silt
The skull of Bison Bob, an extinct steppe bison (B. priscus), sits in some silt on the bank of a river in the National Petroleum Reserve in Alaska in 2012. Photo by Pam Groves.

“This was an exciting find,” beamed Groves who, with Mann, was contracted by the BLM to perform seasonal work studying megafaunal species and how the climate changed over the millennia. That work included looking for bones exposed along riverbanks by seasonal flooding.

‘Digging’ with buckets of water to thaw the frozen sediments and avoid scratching the scientific treasures, they discovered this wasn’t just some random pile.  This was the virtually complete skeleton of a mature male steppe bison — a very rare find, and a researcher’s mother lode.  

It got better.

 

Woman pouring a bucket of water over bones
BLM seasonal employee and University of Alaska Fairbanks wildlife biologist Pam Groves uses buckets of water to thaw and remove sand and soil from the remains of Bison Bob, an extinct steppe bison (B. priscus) found along a river in the National Petroleum Reserve in Alaska in 2012. Photo by Dan Mann.

The bones still had soft tissue attached, complete with rotting smell and bits of fur. In fact, there was a very real concern the smell, already attracting flies, would attract bears.

 

Bones and fur
Bones and fur protrude from a bluff along a river in the National Petroleum Reserve in Alaska. The remains are from an extinct steppe bison (B. priscus), named ‘Bison Bob’ by researchers, that died approximately 43,000 years ago. Amazingly, there was still connective tissue holding many of the bones together. Photo by Pam Groves.

Special (and smelly) finds like this need a name. They eventually decided on “Bison Bob,” now known as ‘BB’ for short.

“It was a friend of ours who named him,” Groves remembered. “There was already a person named Buffalo Bill [Cody], so he suggested Bison Bob. We liked the alliteration.”

Man holding bison skull
BLM seasonal employee and University of Alaska geologist Dan Mann holds the skull from an extinct steppe bison (B. priscus) found along a river in the National Petroleum Reserve in Alaska in 2012. Named ‘Bison Bob’ by researchers, the specimen is one of the most complete skeletons ever discovered. Bison Bob’s horns have a spread of 43 inches.  For comparison, the average American bison has a spread of 20-26 inches.
Woman holding bison vertibrae
BLM seasonal employee and University of Alaska Fairbanks wildlife biologist Pam Groves holds vertebrae, still attached to each other by soft tissue, from an extinct steppe bison (B. priscus) found along a river in the National Petroleum Reserve in Alaska in 2012. Researchers named their find Bison Bob. Photo by Dan Mann.


Robert King, BLM Alaska’s State Archaeologist, oversees archaeological and paleontological permitting and studies on BLM public lands in Alaska. It’s his job to make sure resources like fossils, ancient bones, and cultural sites are properly preserved while also being available for scientific study.

“Bones and fossils may contain clues to the amazing lifeforms of the past,” King explained. “This specimen will be available for future types of studies that are unknown today — ‘Bison Bob’ will undoubtedly tell us more in the future, and that is exciting.”

Since that initial find, BB has been catalogued and studied, and portions are stored frozen at UAF. Carbon dating places the age of his remains at approximately 43,000 years old, pre-dating the earliest known human presence in North America. He was 12 years old when he died, had great teeth with very little wear, and didn’t migrate.

“He was kind of lazy,” Groves laughed.

 

Woman standing along a bluff
BLM seasonal employee and University of Alaska Fairbanks geologist Dan Mann stands near the location of Bison Bob’s skeletal remains in 2012.  Much of the steppe bison’s remains were found inside a bluff over the bank of a river in the National Petroleum Reserve in Alaska. Photo by Pam Groves.

Groves said isotopic analysis of the keratin around the base of one of the horns suggests he didn’t migrate, which means he probably had a good food source. She said that he showed no obvious signs of chronic illness, none of his bones were broken, he didn’t die from old age, and he wasn’t killed by a predator.

“We’re still not sure how he died,” Groves expanded.  “We’re still working on the data.”

That analysis demonstrates one of the more valuable scientific aspects of BB — the fact that the soft tissue and bones have been frozen almost the entire time since his death.

“In bones like these that have been frozen,” Groves explained, “the DNA is pretty well preserved, so it’s often possible to get nuclear DNA as well as mitochondrial DNA.”

 

Bison bones and horn sticking out from bluff
Bones and a horn protrude from a bluff along a river in the National Petroleum Reserve in Alaska. The remains are from an extinct steppe bison (B. priscus), named ‘Bison Bob’ by researchers. Photo by Dan Mann.

This is exciting stuff for fans of Jurassic Park© and scientists alike.  While the nuclear DNA (from the cell’s nucleus) isn’t preserved well enough to make a clone, it can still offer insights into genetic differences that have developed over the millennia.

All of this makes BB an important specimen requiring special attention.

The most recent request for small pieces of BB (two 4-gram samples) came from the University of California Santa Cruz. There, scientists specializing in ancient DNA will test how much degradation happens over a given time period. The experiment will contrast frozen and room-temperature samples from BB and another set of steppe bison remains, ‘Blue Babe’.  According to UCSC, scientists hope the data collected will offer solid statistics that will inform recommendations regarding correct storage of future finds.