Ancient teeth provide clues to mystery

Monica Tromp

By John Gibb

oft.co.nz

Dunedin researchers have used 3000-year-old teeth to solve an ancient banana mystery linked to the last part of the planet to be settled by humans.

A discovery by University of Otago scientist Monica Tromp has provided the earliest evidence of humans transporting the banana to Vanuatu, and later cultivating it there, about 3000 years ago.

“It’s quite exciting,” Dr Tromp said.

In an article published this week in Nature Human Behaviour, she reported finding microscopic particles of banana and other plants trapped in the calcified dental plaque of Vanuatu’s first settlers.

“One of the big advantages of studying calcified plaque, or dental calculus, is that you can find out a lot about otherwise invisible parts of peoples lives.”

“Plaque calcifies very quickly and can trap just about anything you put inside of your mouth — much like the infamous Jurassic Park mosquito in amber,” she said.

She used a microscope to look for microparticles in the plaque, scraped from the teeth of 32 skeletons.

Dr Tromp is senior laboratory analyst at the university’s Southern Pacific Archaeological Research (SPAR), and the finds come from 3000-year-old skeletons at the Teouma site on Vanuatu’s Efate Island.

Teouma is the oldest archaeological cemetery in Remote Oceania, a region which comprises Vanuatu and many other islands, including Hawaii and New Zealand.

At Teouma, lime-rich graves have preserved the plaque and archaeological materials often destroyed elsewhere by hot and humid climates.

There has been debate about how the earliest settlers from the Lapita cultural complex survived on Vanuatu, and it was believed plants and animals were brought with them on canoes.

However, Dr Tromp’s study — part of her PhD research through the university’s anatomy department — was the first to find direct evidence of these plants at Teouma.

Among the article’s co-authors were Profs Elizabeth Matisoo-Smith and Hallie Buckley, and Dr Rebecca Kinaston, also of the department.

 

 

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Researchers: Bananas too inbred to fight disease

Topic: Banana’s, Ancient fruit-gone the way of modern man

 

Geographical distribution of M. balbisiana and subspecies of M. acuminata, the wild ancestors of cultivated bananas.

 

Bananas have
been an important food for humans for at least 7,000 years, but the most popular
types are sterile varieties that make farming easy but hold little genetic
diversity – a recipe for disaster in the face of plant disease, a paper by
scientists from Australia and Europe finds.

The researchers, writing in this week’s edition of the journal Proceedings of the National Academy of Sciences, traced
early banana cultivation to the Kuk swamp of New Guinea around 5,000 BC. The plants spread
throughout southeast Asia and into Africa, almost certainly via human
intervention.

Bananas are a crucial source of food for tropical and sub-tropical nations,
especially Africa, ranking after rice, wheat and corn in importance. More than
85% of bananas are grown for local consumption. Most are not the sweet dessert
varieties eaten in the west, but starchy plantain-style bananas that must first
be cooked.

The banana probably arose in the islands around Southeast Asia and western
Melanesia. It was hybridized into subspecies that could not have been created
without human intervention – the only way to grow more of these bananas is to
take a shoot from a banana plant, as the seeds are generally not viable.

This means that most banana plants are clones, with no genetic variety. A
good example is today’s Cavendish, the main banana sold in the United States and
Europe. All come from clones of the same tree and all are genetically
identical.

The problem with having so many people rely on a few strains of an important
food crop is that they are very venerable to disease. For example, up until the
1950s most bananas eaten in the United States were the Gros Michel
type, which was wiped out by a fungal disease known as Panama disease.

As the researchers say in their paper:

Current global production of more than 100 million tons is based on
large-scale vegetative propagation of a small number of genotypes, which derive
from only a few ancient sexual recombination events. These genetically
restricted and inflexible clones are particularly susceptible to diseases,
pests, and current ecological changes.

Plant breeders need to understand the “sequence of crossings and selections
that occurred minimally during the past 6,500 years” so that they can find other
crosses that can withstand disease and pest outbreaks that might hit this
important plant, they say.

Original Article:

usatoday.com

By Elizabeth Weise

 

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