Watch one of the best true crime stories ever, leading SpareTag.com to reflect on ethical use of DNA evidence from CSI forensics to mosquito eradication
True crime story better than CSI TV shows
The video was inspired by a true story reported in the minutes of the International Society for Forensics Genetics assembly held in 2006. This true story took place in Sicily after the discovery of the corpse of a transsexual prostitute near a beach. The main suspect was a business man living in a faraway neighborhood. The day of the murder, his car had been seen near the beach.
(SPOILERS:) From the blood of one dead mosquito at the home of the business man, the forensic police was able to identify the DNA of the victim. Moreover, investigators were able to verify that the mosquito specie would not have been able to fly the distance from the beach to the suspect house on its own. Hence, the presence of the dead mosquito was an irrefutable proof of the connection between the suspect and the victim. Combined with sand and other vegetal fragments from the beach also discovered at its home, the jury found the business man guilty of murder.
Top 5 frequently asked question about mosquito
This is a true but unusual story, as mosquitoes are more likely to be the active murderer than the passive witness. In effect, approximately 725 000 people die each year from disease carried by mosquitoes, such as malaria, dengue, yellow fever, west nile virus and other chikungunya. Accordingly, mosquitoes are far more efficient killers compared to sharks (only 10 human kills in 2013) or wolves (average of 7 mortal attacks per year) that nonetheless receive more airtime.
Fortunately, not all mosquito bites bring death, otherwise humanity would not have evolved this far. Indeed, the relationship is quite long. The oldest mosquito specimen we found was caught in amber some 80 million years ago in Canada. This conflicted, but well understood, relationship continues to drive us crazy every day.
1. Why do Mosquitos bite?
Only the female mosquito bites. She needs the proteins from the blood to lay her eggs, while male mosquitoes feed on nectar harvested from flowers. Although, not all female mosquitoes are attracted to humans. Of the 3,500 species, only a couple hundred feast on human blood as the rest lives in forests and sustains on animal blood.
2. Why are some people more prone to mosquito bites than others?
Well, it seems like not all blood proteins are equal. Mosquitoes read the blood type from chemical signals secreted by 85% of the people on their skin. The prudent 15% not sharing blood information are more likely to be ignored. But for the rest of us, Type O blood is targeted twice as often as those with Type A. Type B blood is somewhere in the middle.
3. Why do Mosquitos buzz in our ears?
Mosquitoes detect their prey from exhaled carbon dioxide up to 100 feet away. Since human breath through their nose and mouth, mosquitoes are attracted to our heads. By the way, tall or obese people who exhale more CO2 gas are more prone to getting attacked than children or underweight people.
4. Why do we itch after being bitten?
When a female mosquito inserts her mouth trump, called proboscis, into the victim’s skin, she injects some saliva. The saliva serves as an anticoagulant to keep the blood liquid and drinkable. In most of us, the foreign fluid triggers a natural immune response which results in the production of histamines. The following chemical reaction results in the dreaded itch. Diseases, such as malaria, are transmitted to human through the saliva injected by the contaminated mosquito.
5. Why can’t we eradicate mosquito once and for all?
Hmm, that’s the ultimate ethical question arising every time humans try to play gods. A British biotech firm has patented a method of breeding genetically-modified male mosquitoes. The GMOs are then released in the wild in large quantities. After mating with wild females, their offspring larvae die before being able to fly or bite, reducing quickly the population. While appealing to fight dangerous disease, some scientists are worried about the unknown effects on the ecosystem. the eradication of mosquitoes could induce a dramatic change in the food chain for many species including spiders, salamanders, frogs, fish and birds. Others are concerned about uncontrolled natural mutation of such genetically modified organisms into a more fearful transmitter of disease.
Slapping conclusion to our mosquito true story
Voila! We went full circle from the DNA science helping to solve the murder of a single man to the DNA science helping to mass murder entire species. Will we be able to make the best use of this technology for the greater good? Well, to echo the punch line of the video:
“Before swatting your next mosquito, be sure you have a clear conscience”