Posts Tagged ‘evolution’

Nature Ramble

We hear about animals all the time, big animals, small animals, endangered animals, lions, tigers, rhinos, birds and whales. But there are animals that we don’t hear about that often, if ever…

Narwhal’s tusk is super sensitive

Narwhals’ distinctive long tusks are super sensitive, research has found.

The whales are known for their tusks which can reach 2.6m (9ft) in length, earning them comparisons with mythological unicorns.

The tusk is an exaggerated front tooth and scientists have discovered that it helps the animals sense changes in their environment.

Experts suggest males could use the tusks to seek out mates or food.

The results are published in the journal The Anatomical Record.

Dr Martin Nweeia from the Harvard School of Dental Medicine, US, undertook the study alongside an international team of colleagues.

Through the years, many theories have tried to explain the function of the narwhal’s impressive tusk.

“People have said it’s everything from an ice pick to an acoustic probe, but this is the first time that someone has discovered sensory function and has the science to show it,” said Dr Nweeia.

More recently, experts have agreed that the tusk is a sexual characteristic because it is more often exhibited by males and they appear to use them during fights to assert their social hierarchy.

But because the animals are rarely seen, the exact function of the tusk has remained a mystery.

Previous studies have revealed that the animals have no enamel on their tusk – the external layer of the tooth that provides a barrier in most mammal teeth.

Dr Nweeia and the team’s analysis revealed that the outer cementum layer of the tusk is porous and the inner dentin layer has microscopic tubes that channel in towards the centre.

In the middle of the tusk lies the pulp, where nerve endings which connect to the narwhal’s brain are found.

“Although it’s a rigid tooth, it has a very permeable membrane,” said Dr Nweeia.

He explained that because of this structure, the tusk is sensitive to temperature and chemical differences in the external environment.

The researchers proved the link when the tusk was exposed to different salt levels in the water and there was a corresponding change in the narwhal’s heart rate.

He described the tusk as “unique” in the animal kingdom because its porous outer layer is usually only found below the gum line in mammals, where it is only exposed by damage or disease.

“The narwhal is the only example documented where teeth are shown to have the ability to constantly sense environmental stimuli that would not necessarily be considered a threat,” he said.

“If you were looking for an ideal and fascinating tooth to study there’s no question this would be it.”

The tusk grows in a counter-clockwise spiral so it does not curve in the same way as an elephant’s tusk but protrudes straight out.

Dr Nweeia is fascinated by the fact that narwhals put all their tooth-growing energy into a single tusk rather than having a set of teeth to help them eat their diet of large fish, such as halibut.

His previous studies of narwhal skulls and tusks held in museums revealed that the distinctive tusk is the left canine tooth that erupts through the upper lip of males.

Their right canine tooth remains embedded in their skull and in females neither of these teeth usually erupt; though in some rare cases they have a pair of tusks reaching up to 30cm long.

Narwhals are instantly recognisable in Arctic waters

It remains unclear whether the animals have evolved the tusk’s sense functions or whether it is an evolutionary throw back.

“We’re just looking at one time frame in evolutionary history,” said Dr Nweeia.

“We don’t know if this is a sensory organ that is gaining more function, or is this a sensory function that is losing some of its ability?”

He added: “It’s an incomplete puzzle and basically we’ve added a few important pieces.”

The dentist suggests the sensory ability of the tusk might have advantages for males as they could use it to detect where females are, whether they are ready to mate, or how to find food for newborn calves.

His research is now focusing on traditional knowledge, asking hunters in the high Arctic for their observations in the hope that more information on the secretive animals’ behaviour can unravel the mystery of the narwhal’s tusk.



Make you Fink on Friday

Two stories today, both different, but both could lead to our extinction.

A vicious circle, climate change apparently increases violence, and traits like selfishness are not valued in evolution…

Firstly, violence.

Rise in violence ‘linked to climate change’

The researchers believe that war and personal conflicts are links to shifts in climate

Shifts in climate are strongly linked to increases in violence around the world, a study suggests.

US scientists found that even small changes in temperature or rainfall correlated with a rise in assaults, rapes and murders, as well as group conflicts and war.

The team says with the current projected levels of climate change, the world is likely to become a more violent place.

Read more on BBC

Selfish traits not favoured by evolution, study shows

Humans and animals could not evolve in a co-operative environment by being selfish, scientists say

Evolution does not favour selfish people, according to new research.

This challenges a previous theory which suggested it was preferable to put yourself first.

Instead, it pays to be co-operative, shown in a model of “the prisoner’s dilemma”, a scenario of game theory – the study of strategic decision-making.

Published in Nature Communications, the team says their work shows that exhibiting only selfish traits would have made us become extinct.

Read more on BBC

Two seemingly linked theories, one that man is affecting climate change and that that climate change can lead to a rise in violence, two, that selfishness and that means to me meanness and violence as well, are not favoured by Mother Nature.

If this is the case, are we not the authors of our own demise?

A paradox.

Satireday on Eco-Crap


Make you Fink on Friday

We think we can outsmart nature.

But we are wrong, so terribly wrong. Nature wins every time. It doesn’t matter whether we are talking about floods, erosion or even the smallest things like cockroaches.


Yes, that ghastly insect we all love to hate.

They make women scream, men stamp on them at every turn, we poison them and try to eradicate them, but they are still with us; and Mother Nature is making sure they will be with of us for a long long time yet.

Cockroaches lose their ‘sweet tooth’ to evade traps

Dr Coby Schal: The cockroaches spit out the glucose “like a baby rejects spinach”

A strain of cockroaches in Europe has evolved to outsmart the sugar traps used to eradicate them.

American scientists found that the mutant cockroaches had a “reorganised” sense of taste, making them perceive the glucose used to coat poisoned bait not as sweet but rather as bitter.

A North Carolina State University team tested the theory by giving cockroaches a choice of jam or peanut butter.

They then analysed the insects’ taste receptors, similar to our taste buds.

Researchers from the same team first noticed 20 years ago that some pest controllers were failing to eradicate cockroaches from properties, because the insects were simply refusing to eat the bait.

Dr Coby Schal explained in the journal Science that this new study had revealed the “neural mechanism” behind this refusal.

Jam v peanut butter

In the first part of the experiment, the researchers offered the hungry cockroaches a choice of two foods – peanut butter or glucose-rich jam [known as jelly is the US].

“The jelly contains lots of glucose and the peanut butter has a much smaller amount,” explained Dr Schal.

“You can see the mutant cockroaches taste the jelly and jump back – they’re repulsed and they swarm over the peanut butter.”

In the second part of the experiment, the team was able to find out exactly why the cockroaches were so repulsed.

The scientists immobilised the cockroaches and used tiny electrodes to record the activity of taste receptors – cells that respond to flavour that are “housed” in microscopic hairs on the insects’ mouthparts

“The cells that normally respond to bitter compounds were responding to glucose in these [mutant] cockroaches,” said Dr Schal.

“So they’re perceiving glucose to be a bitter compound.

“The sweet-responding cell does also fire, but the bitter compound actually inhibits it – so the end result is that bitterness overrides sweetness.”

Highly magnified footage of these experiments clearly shows a glucose-averse cockroach reacting to a dose of the sugar.

“It behaves like a baby that rejects spinach,” explained Dr Schal.

“It shakes its head and refuses to imbibe that liquid, at the end, you can see the [glucose] on the side of the head of the cockroach that has refused it.”

Read more

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So, we’re not about to be rid of these horrid creatures anytime soon.

Mother Nature is winning the battle.


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