Its the ability of our immune system to remember past infections and pass this memory on to our kids, that allows us to survive infectious diseases.
Picture: Freeimages.com
Its easy to feel our survival is under threat from new and emerging infectious diseases that are going to wipe out the human race, or at least end our current way of life. The recent outbreaks of Ebola in West Africa re-ignited our interest in pandemics and reminded us of our potential frailty in the face of an overwhelming enemy.
With so many microbes capable of hijacking and destroying us, how are we as a species still enduring?
Humans are unique in the world. We are avid collectors of infectious diseases acquired from our environment throughout our evolution.
We all just want to survive and procreate
We share with our invaders a need to survive and propagate our genes. Infectious pathogens, such as bacteria and viruses, are parasitic they have to find and infect a susceptible host in order to maintain themselves and propagate. Therefore, its not really in their best interests to kill us. Our relationship with pathogens is shaped by our capacity to evolve genetically, to modify our behaviour, or to force the pathogens to evolve so that we all survive.
Viruses such as influenza replicate and spread to new hosts before the original host gets sick (with influenza symptoms such as a sore throat and sneezing), meaning the parasite can survive and thrive in new hosts.
On rare occasions, the death of the host is necessary for the pathogen to reproduce. One example is trichinellosis (also known as trichinosis), which is caused by eating undercooked or raw meat from animals (usually carnivores and omnivores) infected with a worm (nematode).
To survive in the host, the worm constructs a capsule around itself to avoid the immune system. The immature worms in the meat cause muscle weakness and paralysis, and eventually death, in the host. This means the victim is defenceless to predators that may come and gobble it up, thus giving the worm a new host to infect.
This is an old disease that we tackle either by avoiding eating meat (possibly the reason some religions avoid eating pork) or through cultural adaptation such as overcooking.
How weve adapted to win the fight
Evolutionary pressures through Darwinian selection, survival of the fittest, constantly shape life on Earth. This innate ability to adapt has enabled humans to develop defence mechanisms to counter some of the most devastating pathogens.
Malaria is a parasite of red blood cells that is estimated to have caused 429,000 deaths in 2015. When malaria became a human disease (it is thought to originate in primates) is unclear. One thing that is clear is that it emerged long enough ago for humans to evolve innate defences.
Sickle cell mutation is a potentially fatal blood disorder seen mainly in Africa. This mutation in a haemoglobin gene (responsible for red pigment in blood cells) is one of a number of genetic traits that actually protect against malaria. People who have this genetic mutation are protected against malaria and thus likely to reproduce and pass on their evolutionary advantage.
A second genetic mutation that protects humans against malaria affects an essential enzyme for red blood cell function. But individuals with this mutation may also develop life-threatening anaemia (deficiency in the number or quality of red blood cells) due to the destruction of red blood cells as a side effect of treatment with some modern anti-malarial drugs.
Perhaps the most significant and wondrous part of the evolutionary machinery that enables the human race to keep one step ahead of the pathogens is the major histocompatibility complex (MHC). The MHC proteins on the surface of our white blood cells evolved along with the vertebrates (animals with a spine), which makes them our oldest defence mechanism.
We have different types of white cells: mobile ones in the blood (lymphocytes) and resident ones in lymph nodes (macrophages). When there is an infection the macrophages gobble up the bugs and present proteins from the organism on their surface like signals.
The lymphocytes containing MHC molecules that recognise this protein bind on. (Our immune system has memory cells that are produced after vaccination or past infections so we can remember how to fight them next time.) The lymphocytes then produce chemicals that recruit more lymphocytes to help. These multiply and you end up with a swollen gland.
Our bodys ability to remember past infections is one of the reasons the entire population of London didnt perish during the Black Death. MHC molecules are passed on to our offspring, which explains why we have such a wide variety of these molecules. When a disease enters a population for the first time it always more lethal than subsequent introductions because some people are now immune, and people have been born to the survivors.
Not all pathogens make us stronger
Not all co-evolution leads to changes in human genetics, especially if there is no impact on our ability to procreate. Human tuberculosis is a chronic disease that continues to plague the world with little evidence that humans have developed any ability to resist infection. This is interesting because it is likely to have co-evolved with us from Neolithic times.
We will continue to face new and emerging diseases. So far, our capacity to adapt and respond has served us well. But some scientists believe humans are no longer evolving due to the removal of many selection pressures, most important things that cause premature death.
The question is whether we are up to the challenges posed by what comes next. Perhaps the most pressing issue facing us now is that bugs seem to be evolving faster than we can create things to kill them known as antimicrobial resistance.
The spectre of life without antibiotics is terrifying given we never did overcome bacterial infections through evolution. Instead, we used our ingenuity. Our future will reflect how well we exercise our collective intellect and will to dodge this bullet.
Written by Simon Reid, Associate Professor, Communicable Disease Control, The University of Queensland.
This article was republished courtesy of the World Economic Forum.
Read the original here:
This is how humans have evolved to fight the bugs that make us ill - Eyewitness News
- June 11th At Westport, CT: Federal Red Flags, HIPAA Security Rules and Fraud Prevention - November 7th, 2009 [November 7th, 2009]
- Do not learn Dvorak! - November 7th, 2009 [November 7th, 2009]
- You Can’t Solve Problems By Making It Illegal To Have The Problem - November 7th, 2009 [November 7th, 2009]
- A Force Fix for Healthcare - November 7th, 2009 [November 7th, 2009]
- Yahble, HIT, Bubblecon, BIZDEV!, Solid State - November 7th, 2009 [November 7th, 2009]
- 15 things that suck about the Palm Pre - November 7th, 2009 [November 7th, 2009]
- What an Indie Genomics Lab Looks Like - November 7th, 2009 [November 7th, 2009]
- Practice Fusion: Class D Felony? - February 26th, 2010 [February 26th, 2010]
- Practice Fusion Responds - March 7th, 2010 [March 7th, 2010]
- Practice Fusion: Do the math: $44,000 is a LIE - March 10th, 2010 [March 10th, 2010]
- How Much Until Doctors Approve of 23andMe? - March 10th, 2010 [March 10th, 2010]
- Biochemicals as Media, Not Methods - March 10th, 2010 [March 10th, 2010]
- More Practice Fusion Reality Distortion - March 10th, 2010 [March 10th, 2010]
- Same Test Results: 23andMe is Myriad is BRCA is Medicine - March 12th, 2010 [March 12th, 2010]
- BRCA is 23andMe is Myriad is Medicine - March 13th, 2010 [March 13th, 2010]
- Getting Serious About Genomics as Common Medical Practice - March 15th, 2010 [March 15th, 2010]
- The New John Mackey of Genetics: Linda Avey? - March 15th, 2010 [March 15th, 2010]
- Keep the Medical, Well, Medical - March 16th, 2010 [March 16th, 2010]
- If 23andMe shuts down, it won’t be for some mundane reason like the bills weren’t paid - March 16th, 2010 [March 16th, 2010]
- If I Run A Medical Practice, How Do I Use A 23andMe? - March 17th, 2010 [March 17th, 2010]
- 23andMe Contract in Bad Faith - March 19th, 2010 [March 19th, 2010]
- Doctors CANNOT Use 23andMe Due To 23andMe’s Bad Faith Contract - March 20th, 2010 [March 20th, 2010]
- Pathway Compared to 23andMe and Navigenics - March 22nd, 2010 [March 22nd, 2010]
- There’s a Word for “Views Differ” When One View Is The State - March 24th, 2010 [March 24th, 2010]
- Association for Molecular Pathology, et al. v. USPTO, et al. – Opinion - March 29th, 2010 [March 29th, 2010]
- Birth of a Super Villain - April 3rd, 2010 [April 3rd, 2010]
- “Medical Products” like 23andMe must not become the new “Financial Products” - April 4th, 2010 [April 4th, 2010]
- How I Would Apply Genomic Technology In Clinical Use Today - April 5th, 2010 [April 5th, 2010]
- Gmail Enterprise: World’s Best EMR - April 6th, 2010 [April 6th, 2010]
- Brief Primer on Health Law Compliance - April 9th, 2010 [April 9th, 2010]
- Spoiler: You ARE the “Valids” - April 9th, 2010 [April 9th, 2010]
- Rachel Lehmann-Haupt Line by Line Take Down - April 9th, 2010 [April 9th, 2010]
- Is Medicare Bankrupt? What the Hell Is Going On? - April 17th, 2010 [April 17th, 2010]
- The Big Shuffle: Medicare Cuts Rates by 21.3% (but not “technically”) - April 17th, 2010 [April 17th, 2010]
- “Tech Hiring Binge” == “Fear for Your Job, Nerds” - April 18th, 2010 [April 18th, 2010]
- How Bad is Bad? $.20 on the Private Medical Insurance Dollar - April 20th, 2010 [April 20th, 2010]
- Update: How Bad is Bad? It Used to Be $.45 on the Medical Insurance Dollar - April 20th, 2010 [April 20th, 2010]
- World’s Best “EMR” for $1000: Google Spreadsheets + iPad - April 21st, 2010 [April 21st, 2010]
- Don’t Insult Me with your “AOL Keyword” Strategy, Google Health - April 21st, 2010 [April 21st, 2010]
- How to Play LAWGAMES - April 23rd, 2010 [April 23rd, 2010]
- Top 4 Predatory Schemes Encroaching on American Medicine: Part 1 - April 25th, 2010 [April 25th, 2010]
- What’s the Big Deal About iPads? - April 27th, 2010 [April 27th, 2010]
- Got Google Android for Google I/O - April 27th, 2010 [April 27th, 2010]
- Google Enterprise meets HIPAA and HITECH Compliant Laws - April 29th, 2010 [April 29th, 2010]
- Pixels of Accuracy CHALENGE: Diagnostic Medical Imaging - April 29th, 2010 [April 29th, 2010]
- 23andMe Launder AlioGenetics Doesn’t Even Bother to Remove 23andMe Logo - April 30th, 2010 [April 30th, 2010]
- Anthem of CT Denies $600 Until “Subscriber Responds to our Coordination of Benefits Questionnaire” - May 1st, 2010 [May 1st, 2010]
- Apple And Google Team Up To Launch Revolutionary Mobile Health System - May 1st, 2010 [May 1st, 2010]
- Funny Pictures from This Year Building the Medical Practice - May 6th, 2010 [May 6th, 2010]
- Remote Medical Video Monitoring on iPad and iPhone - May 7th, 2010 [May 7th, 2010]
- Google Calendar Overhead Waiting Room Display - May 7th, 2010 [May 7th, 2010]
- Various Whiteboards on Solid State Medical Operations - May 7th, 2010 [May 7th, 2010]
- The Raw Facts about Counsyl - May 7th, 2010 [May 7th, 2010]
- Brawndo: Still Mutilating Thirst, Still Not Yet Sold at the Stop-n-Shop Pharmacy - May 9th, 2010 [May 9th, 2010]
- Video: Google Enterprise to Outsource Medical Administration - May 9th, 2010 [May 9th, 2010]
- Gattaca: “The Matrix” of Genomics - May 11th, 2010 [May 11th, 2010]
- 23andMe Now Diagnoses Fatal Tay-Sachs Disease - May 12th, 2010 [May 12th, 2010]
- Why Was Pathway Targeted for FDA Enforcement and Not 23andMe? - May 15th, 2010 [May 15th, 2010]
- John Dolan on Aging and the Horrifying Conclusion of GWAS - May 16th, 2010 [May 16th, 2010]
- Sam R. Riley Wants To Tell You About Practice Fusion - May 17th, 2010 [May 17th, 2010]
- Response to “Genomic Medicine: Lost” - May 19th, 2010 [May 19th, 2010]
- Death And Taxes: CMS to IRS - May 19th, 2010 [May 19th, 2010]
- Please Stop Antagonizing the AMA - May 26th, 2010 [May 26th, 2010]
- Dan Vorhaus, Attorney At Law, Legally Advises Medical Doctors Can Use 23andMe To Provide Medical Advice - May 28th, 2010 [May 28th, 2010]
- Singularity Summit 2010 in San Francisco to Explore Intelligence Augmentation - June 7th, 2010 [June 7th, 2010]
- OpenPCR: DNA amplification for anyone - June 10th, 2010 [June 10th, 2010]
- FDA sends letters to 5 genetic testing companies - June 11th, 2010 [June 11th, 2010]
- Amazon And The NIH Team Up To Put Human Genome In The Cloud - March 31st, 2012 [March 31st, 2012]
- ReproSource Comments on New Study Linking Infertility to Genetics - April 25th, 2012 [April 25th, 2012]
- Genetics 101 Part 1: What are genes? - Video - April 30th, 2012 [April 30th, 2012]
- Red Ice Radio - David Icke - Hour 1 - The Manipulation of Humanity - Video - April 30th, 2012 [April 30th, 2012]
- Genetics Part 5: Human Genetic Disorders - Video - April 30th, 2012 [April 30th, 2012]
- C2CAM - The Nephilim, Genetic Manipulation - April 30th, 2012 [April 30th, 2012]
- Human Nature talk with Robert Sapolsky, Gabor Mate, James Gilligan, Richard Wilkinson - Video - April 30th, 2012 [April 30th, 2012]
- Human Genetic Diseases - Video - April 30th, 2012 [April 30th, 2012]
- Alien Scientist on Genetics, Implants - April 30th, 2012 [April 30th, 2012]
- Research and Markets: Genetics, 6th Edition International Student Version Continues To Educate Today's Students for ... - May 4th, 2012 [May 4th, 2012]
- Myriad Genetics to Present at the Bank of America Merrill Lynch 2012 Health Care Conference - May 4th, 2012 [May 4th, 2012]
- Genetics may explain some people's dislike of meat - May 4th, 2012 [May 4th, 2012]
- 'Blond Genes' May Vary Around the World - May 4th, 2012 [May 4th, 2012]