Tag Archives: biology

Earliest image of men and dogs – a brief history of our friendship

Posted on November 20, 2017 by | Leave a comment

“I think my Instagram should be renamed, like the album of my Husky.” Said my friend Katrine last week. “That’s why I never post on Instagram,” I replied. “I don’t have a friend that close to me.” Humans’ fevers for dogs spread everywhere on the internet, and dogs have entitled “humans’ best friends” for a very long time. In fact, human relationship with dogs is a very long story, and we can trace it way back when the world population was only about 5,000,000.

 

A paper published in Journal of Anthropological Archaeology last month revealed that sandstone carved images of humans and dogs were discovered in northwestern Saudi Arabia. Scientists suspected the images to be world’s first images of humans and dogs.

 

“earliest image of men and dogs” from paper in Journal of Anthropological Archaeology

 

In this image, the man, with an arrow in his hand, has dogs following him hunting the big mammals together. Scientists noticed that there are very obviously carved lines between the man’s waist and the dogs’ necks. Similar lines appeared in the other images at the site, and researchers stated that the lines were probably leashes, and dogs were already domesticated, trained to assist human hunting activity at the time. From the weathering condition of rocks and the sequence of drawings, scientists concluded the art is at least 8000 years old.

 

“It’s the only real demonstration we have of humans using early dogs to hunt.” Said Melinda Zeder, an archaeozoologist at the Smithsonian Institution National Museum of Natural History, Washington, D.C.

 

Scientists have hypothesized the collaboration between dogs and hunters a long ago. In fact, in an earlier study that provided a hypothesis of dogs’ domestication for hunting, evidence indicated mammoths were massively killed at a time when humans did not have compatible weapons in Europe, and dogs were likely accompanying hunters. Dogs, evolved and inherited from wolves, could identify preys by scents and growl in groups to hold preys in place. In fact, another research team also found in Japan that humans from 2,400-16,000 years ago buried their dogs with shreds of evidence that they were hunting partners.

 

Today is always the consequence of yesterday. We now consider dogs are such good friends of humans because the friendship arose since a very long time ago. In the past, humans fed and sheltered dogs while dogs assisted humans for hunting. It is domestication but also collaboration, with the common goal of survival for both men and dogs. It is the result of natural selection. Today, aside from gaining “likes” on social media, dogs are still helping men on a lot of practical aspects such as guidance for the disable, therapeutics, DEA detection. Like the carved images on the stone, our friendship with dogs never faded as time went by.

“A guide dog working” by Yahoo! Accessibility lab from Flikr. CC BY-SA 2.0

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Youtube: How dogs became our best friends

-Zhou Wang

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Salmons near Seattle found high with drugs, and should you be concerned?

Posted on November 13, 2017 by | 2 comments

Assuming you are a sushi or seafood lover, will you be shocked if I tell you the salmons near Seattle has found to have of multiple drugs, including cocaine in their tissues? Although you actually don’t need to worry about your health this time, some other effects may still worth concerning.

Salmon. credit: Pexels

A study lasted from 2014 to 2016 has examined the contaminants in three estuaries in Puget Sound near Seattle by collecting both water sample and juvenile Chinook Salmon samples. The scientists found that the juvenile Chinook Salmon’s tissue contains many drugs and other chemicals, including Prozac, Advil, Benadryl, Lipitor, BPA, even cocaine. The estuaries’ water also contains 81 types of drugs, cosmetic products, which are higher than the expected concentrations.

Salmon and water bodies contain the chemical products. Source: http://www.sciencedirect.com/science/article/pii/S0269749116300884

The variety of the compounds inside salmon and water is from multiple factories in the regions producing a wide range of products, including pharmaceutical, personal care products, and current use pesticides. Multiple chemicals then are ejected into the water bodies and the organisms from the discharged water from the factories’ wastewater treatment plants.

Fortunately for us, the concentration of individual compounds in the organisms and water would be too low to affect human health. Also, there are multiple other salmon species to choose, like sockeye salmon, so that people would not need to eat juvenile Chinook salmon.

However, it is estimated that the salmons’ survival rate would be decreased by around 50%. The drugs could inhibit the salmons’ immunity, and make them more susceptible getting diseases and/or make them become less fit. This could also give them a hard time feeling from their predators, and thus increase the salmon population’s death rate.

Also, most of the compounds and products found in salmon tissues are in fact approved to use, or considered as non-toxic, it is quite common for them to be discharged from a wastewater treatment plant. Thus, only a small proportion of the chemicals are monitored or regulated in the estuary environment, while there could be hundreds of other chemicals/products presenting the water and organisms. Therefore, the toxicity effects might have been underestimated, as the “non-toxic compounds” could interact with each other, and increase their overall toxicity to be harmful to humans.

In a word, even though we are being lucky enough not to be affected by the drug-contained salmons this time this time, it is yet unclear about the overall effects of the multi-products-contaminated waterbodies. If we don’t work on to improve the wastewater monitoring and regulation system, maybe the water contamination will eventually affect ourselves.

 

-Lilo Wang

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WAKE UP. Take a coffee nap.

It’s late afternoon now. You had your perfect cup of coffee in the morning, but the day has taken its toll on you. Shall you go for another cup? Or perhaps a nap to wake you up?

I recommend to you not either or, but both! Yes, the best of both worlds: the coffee nap.

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Coffee Nap: a cup of coffee then a nap (see, I google “coffee nap” and I get sleeping animals). 

Left: Wikimedia Commons – Julius Schorzman.  https://commons.wikimedia.org/wiki/File:A_small_cup_of_coffee.JPG

Right: Pixabay – Scheeze. https://pixabay.com/en/cat-sleeping-nap-bed-portrait-pet-2092451/

Why aren’t coffee naps a trend? Scientists discovered two decades ago that drinking a cup of coffee, then napping for 20 minutes will boost your energy way more than a regular nap or coffee. Sleepy people who took a 15-minute coffee nap before being tested in a driving simulator scored higher. Research also says that coffee naps wake you up more than face washing, bright light, taking breaks, and coffee or napping separately.

So how do coffee naps work? First let’s learn how caffeine wakes you up.

Caffeine, a chemical in coffee, enters your bloodstream about twenty minutes after you drink it. It makes it way to your brain where it fills receptors which are normally filled by adenosine, another chemical. This happens because caffeine is similarly shaped to adenosine.

The chemical structures of caffeine and adenosine. Note how similar they are: they both have N (Nitrogen), O (Oxygen), and ring structures in their chemistry.

Wikimedia Commons: Edgar181. https://commons.wikimedia.org/wiki/File:Caffeine_and_adenosine.png

What does adenosine do? Adenosine builds up in your brain with each moment you are awake, and when it fills receptors it makes you sleepy. But when caffeine blocks adenosine, you don’t become sleepy.

A nap works in a similar way. Sleep doesn’t block, but removes adenosine from the brain. But if you sleep for more than twenty minutes, you fall into a deep sleep and become less alert when you wake up. So short, power naps are actually effective!

Now let’s put caffeine and napping together. First your nap removes adenosine from your brain so the receptors are less filled. Then, at twenty minutes, caffeine comes in and blocks more receptors than it could have without the help of adenosine. The result? Your afternoon rescue.

So take that coffee nap! Even half-sleeping for twenty minutes will be helpful, and you can also drink other caffeine beverages.

As for me, even though I still don’t drink coffee, and can’t nap either, I will give it a shot. Let me know how it goes for you!

Cheers,

Ivy Wu

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Posted on November 2, 2017 by in Admin

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Why people have 5 fingers?

Posted on October 31, 2017 by | 5 comments

Have you ever wondered why you have five fingers?? We have been using our hands for more than twenty years and you may have the same question as i do which is why we have 5 fingers.

To better understand the reason, let’s look at a special case of “polydactyly“. In short, polydactyly refers to the situation where there are more than five fingers in a hand (or foot). There are two types of polydactyly which refer to Type A and Type B. In Type A, the extra finger can function properly like other fingers and have a complete bone structure.  In Type B, the extra finger is non functional and  seems to be “floating”.

Type A of polydactyl http://https://en.wikipedia.org/wiki/Polydactyly

Type B of polydactyly http://https://en.wikipedia.org/wiki/Polydactyly#/media/File:Polydactyly_Left_Hand.jpg

To answer our question in the beginning, we have to know the cause of Type A. The duplication of the entire finger is due to an abnormal function of a gene called “Sonic hedgehog” gene or”SHH” gene which plays an important role in the growth of digits on limbs and organization of the brain. During the fifth week of an embryo development, SHH gene will synthesize a signalling protein called  Sonic hedgehog protein which act on the ulnar side of the “hand” (at the black dot in the picture) and fingers start to form.

Hand of an embryo
https://dissolve.com/video/Human-embryo-close-developing-face-rights-managed-stock-video-footage/002-D30-11-319

When the concentration of the SHH signalling protein is lower than common level, less than five fingers will form. When the concentration of the SHH protein is too highly, it will result in Type A of polydactyly.

This is the reason of how five fingers formed, but you may still wondering that why five-finger structure is common. This is the result of evolution. About 380 million years ago, quadrupedalism can have six, seven even eight fingers depending on different species. Due to evolution, it has been simplified into a five-finger structure which ensure both the flexibility and the grasping ability. This is the reason why we all have five fingers not six or four.

Written by Xuan Wang

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