Wednesday, October 17, 2012

Chimpanzees Need Help with Sex, Too

The art of mating takes on one level of intelligence, if any level of intelligence.  The use of external tools to move sex along takes on another, and it seems that humans are not the only species to take advantage of these.

John Tierney of the NY Times says, "only Homo sapiens seemed blessed with the idle prefrontal cortex and nimble prehensile thumbs necessary to invent erotic paraphernalia." 

However, it seems that chimps use tools as well.  In 1960, a certain resourceful chimpanzee came under the scrutiny of Jane Goodall near Lake Tanganyika.  It was feasting on termites with a blade of grass that he had poked into a passage in the mound to extract his meal.  The soldier termites would attack the intruding blade, and, knowing this, the chimpanzee would pull blade back out, now spotted with these tasty treats.  

This blade of grass served as a tool, and, "to be classified as a tool, an object must be held in the hand, foot or mouth and used as to enable the operator to attain an immediate goal" (Goodall).

According to Dr. McGrew, professor at the University of Cambridge, a male chimpanzee attracts a female through a distinctive, rasping sound.  The tool used to produce this sound is a leaf or a set of leaves, which the male breaks bit by bit down the midvein as he sits with his legs open to reveal his erection.  He will continue this leaf-clipping ritual until the female comes to mate with him.

Does evolution fall short?  "Considering all that evolution had done to make sex second nature, or maybe first nature, I would have expected creatures without access to the Internet to leave well enough alone", said Tierney.

The Denisovans: A Look into Our Past

According to two recent articles in the LA Times, scientists have discovered and sequenced the genome of one of our close relatives: an extinct people known as the Denisovans, who lived in modern-day Siberia.

The genome itself was sequenced from a tiny DNA sampling extracted from shredded finger bone found in a Russian cave in 2008. A tooth was also found later
-Interesting to note that this sample of DNA gave as much detailed information about the individual as a DNA sample from blood or saliva extracted from a human today.
            -it suggests that the Denisovans had dark skin, brown hair and brown eyes

How the Denisovans fit into our evolution: Homo erectus (1-2 million years ago) à Denisovans, who left Africa as far back as 800,000 years ago à Homo sapiens left Africa perhaps 100,000 years ago

Analysis of this genome will offer insights into our own Homo Sapein history, as well as the unique changes that made us homo sapiens, and evolved us to stray away from the genetic make up of the Denisovans. Although discovering the thousands of tiny genetic differences between the two species, Svante Paabo and his coauthors have already highlighted several differences, including genes involved in writing the brain and ones that are known to be linked to autism.

This discovery leads us to question what other species are out there that can help us answer our complicated and much-debated history. Many say this discovery is just the beginning. However, the study found that about 3 to 5 percent of the DNA in people native to Papua New Guinea, Australia, the Philippines and other islands nearby came from Denisovans

Where we differ:
-About 100,000 places where single nucleotides, the individual building blocks of DNA, have changed so that one type of nucleotide has been swapped out for another
-About 10,000 places where a piece of DNA has been lost, or a new bit added.
-Found 260 changes that would alter a protein’s form by changing one of the amino acids it contains
-Found that we, homo sapiens, have 23 amino acid changes that the Denisovans and monkeys and apes DON’T have. 8 of these have to do with brain function and brain development, which strongly correlates with our ability to create larger, sustainable societies and have larger brains.
Yet at the end of the day, scientist Svante Paabo states, “Unfortunately, at the moment we know too little about the genome to really say what these things mean.”

Tuesday, October 16, 2012

Genes Play Major Role in Primate Social Behavior, Study Finds

A study reported by The New York Times reveals that social behavior among primates is largely determined by genetics.

Scientists at the University of Oxford in England conducted a survey in which they observed two hundred seventeen primate species' evolutionary family trees.  The species they observed have distinct and scientifically-known social structures and behaviors.  What scientists found when they looked at these evolutionary family trees was quite surprising: related species have similar social structures.  This suggests that common ancestry genetically determines social behaviors.

These findings are incredibly important because they come in direct conflict with some of the leading theories of social behavior.  They challenge the theory that social behaviors and structures are determined by the environment.  Researchers found that in spite of vastly different ecology, Old World monkeys still have very similar social systems.  The findings also challenge the social brain hypothesis, which claims that intelligence and brain volume directly correlate with group size, because members of the group must learn how to engage in more complex social relationships.  The findings, however, suggest that there has not been a steady increase over all primate species from small groups to large groups.

The study also verifies the social structure of humans.  As part of the primate family, the organization of human society is likely to have a genetic basis as well.  However, the fact that human society seems to be so socially diverse must be considered.  Scientists of this survey argue that while social behavior among humans too is genetically determined, "cultural variation hides both the social unity of humankind and its biological foundation."

Sunday, October 14, 2012

Evolution Continued

Many people mistakenly believe that evolution is no longer happening in humans. That we have reached the end of our evolution and the species is now stagnate. But this is in no way true! Evolution is still at work and this article in the New York Times is an elucidating report on how mankind has been changing and why it has been changing.

One of the examples they used was “Asian Flush.” When people in China discovered that they could convert cereal into liquor, drunkenness must have posed a threat to their survival. As a result a variant gene that protects agains alchol became prevalent in almost all of China as rice cultivation became universal. The gene transforms the intoxicating effect of alcohol to a chemical that makes people flush. This is an example of how cultural changes are shaping evolution. This population responded on the molecular level to changes in their local environment. East Asians have a genetic variant absent from European and African populations of having thicker hair. This presumably is to help protect themselves from the cold.

A government project called the Hap Map s a way of seeing the force of natural selection across the whole human genome. This is meant to discover the root and patterns of disease/ But it also provides the DNA data to see where evolution is occurring. It appears from data that 13% of our genes have been shaped by recent evolution! Evolution has not reached a standstill, and as our environment continues to rapidly change so will we!

Body Building: Scientists Begin to Make Organs

In Sweden doctors were able to engineer and create a windpipe for a patient with a tumor that was not responding to chemotherapy and radiation. The patient was out of options until Paolo Macciarini had the idea to create a bioartificial windpipe using the patients own cells and plastic. This was the first-of-its-kind procedure in the field of regenerative medicine.

Now the technologies used to create a windpipe are being replicated with more complex organs. Macciarini’s technique was to take the bodies cells and then let them do most of the regeneration. Most of the organs created with this new field of “tissue engineering” were small and hollow organs like the windpipe and bladder.

Artificial organs of the past are almost robotized. This new field seeks to create organs that are not merely machines. At first Macciarini’s lab took cadaver organs and replanted them with the living cells of patients. Then they decided to replace the cadaver scaffold with plastic scaffolds. They gave life to this plastic scaffold by using Macciarini’s stem cells.

This opens the doors for so much more exploration. The windpipe was only the first case of what will hopefully become an accessible and reliable innovation.
Scientist Make Progress in Tailor-Made Organs

Wednesday, October 10, 2012

Infant DNA Testing

A recent article in The New York Times outlines a new method by which an infant's DNA can be quickly and accurately scanned for possible genetic diseases.  This new method was published just last week in the Science Translational Medicine Magazine.  It combines the use of Whole Genome Sequencing (using the Illumina sequencer) with Symptom and Sign-Assisted Genome Analysis.  This method utilizes an infant's symptoms to focus on specific parts of the genome that may carry a mutation that causes a genetic disease.  The entire process can be completed in approximately 50 hours, which makes it a very useful test for quickly determining if an infant has a genetic disease.

Such testing can be extremely helpful in identifying the proper treatment path to take.  For example, in some cases, the genetic information may indicate that the disease is fatal, and thus treatment can be terminated before it becomes unduly costly, but in other cases, the knowledge about a genetic disease may lead doctors to a different type of treatment.  Identification of such diseases can be very economically viable because it can help limit the amount of time an infant stays in the NICU, which is extremely costly.

Despite its obvious benefits, this testing is still very new, and it does have some limitations.  For example, the system is unable to identify dominant genetic diseases, and it also struggles to identify certain types of mutations, such as large deletions.

Tuesday, October 9, 2012

Study Distinguishes Between Different Types of Breast Cancer

In a study published by Nature and sponsored by The Cancer Genome Atlas Network distinguished between four different types of cancer. The study analyzed the tumors from 825 patients making it the largest breast cancer genomics project.

Scientists were primarily researching what is thought to be the most common type of breast cancer that begins in the milk duct. They were analyzing tumors that had not yet metastasized, and from their sample size they found dramatic differences among the tumors. They found a particular type of breast cancer in which the tumor cells more closely resemble basal cells. This discovery changes the way that scientist attempt to treat this type of cancer. Rather than treat basal-like cancers with anthracyclines, this study provides evidence that it might be more efficient to use treatments for ovarian cancer—these treatments are also gentler and are not associated with heightened risk for heart damage and leukemia.

The study also found two other types of breast cancer in the luminal cells in the milk ducts. One kind is associated with a good prognosis and suggests that hormonal therapy is sufficiently effective, whereas those with the other type of luminal cancer, Luminal B might benefit from chemotherapy in addition. The research also found that certain genetic aberations were so strongly associated to each of the different types of luminal subtypes that there may be a causational relationship.

The last type of breast cancer that researchers identified is HER2-enriched. There is a drug to block the gene, Herceptin, leading to a very effective targeted therapy. However, Herceptin is associated with risks so knowing if one has HER2-enriched breast cancer helps doctors tailor treatments to the individual.

To conclude, by specifying the type of breast cancer a person has doctors are now able to better treat the cancer rather than the entire body system. This will be to the benefit of the patient who wont be victim of a chemical cocktail but instead of a targeted treatment.