We know that women live longer than men, but why?

In 2017, the average life expectancy of women in the U.S. was 81.1 years but only 76.1 years for men. Longevity differs by country but the sex disparity is true for all humans and for other species as well.

A study at the University of New South Wales, Sydney published in March 2020 examined the life spans of 229 species and discovered it is related to sex chromosomes.

Across the animal kingdom, individuals with identical sex chromosomes — including women with double Xs — live nearly 18% longer than their counterparts with mismatched chromosomes.

— The Secret to a Long Life? Matching Sex Chromosomes, Science Daily

Among mammals, insects, fish and some reptiles, females have matching sex chromosomes [XX] whereas males do not [XY]. In all of these classes females live an average of 20.9% longer and sometimes a lot longer. The study found that female German cockroaches (Blattella germanica) live 77% longer than males. Ewww!

Among birds and butterflies the arrangement is opposite. Male birds have matching sex chromosomes [ZZ] whereas female birds do not [ZW]. In this case the males live longer, but only about 7.1%.

More study is needed to discover why male birds don’t reach the longer life spans that female mammals and insects are able to achieve.

Learn more at “The secret to a long life? Matching sex chromosomes” in Science Magazine.

p.s. Life expectancy in the U.S. has been dropping since 2014.

(photos from Wikimedia Commons; click on the captions to see the originals)

28 June 2020

Coronavirus is surging in many southern and western U.S. states and has increased in Allegheny County at levels far beyond our experience in late April.

The surge in Pittsburgh is ironic. Allegheny County had zero new cases on 17 June. On 27 June we had 90 new cases. At the time it was the highest single-day increase we’d ever seen. In less than two weeks we squandered two months of effort. And it’s gotten even worse! (see Public Source)

What caused it?

• Good news: Black Lives Matter protests did not cause a surge in cases. Here’s the study.
• Bad news: People, especially young people, are getting too close to each other and not wearing masks. Especially in bars. Texas and Florida are closing bars.

After months of study we now know you’re most likely to catch coronavirus through the air, by proximity and time spent near someone (often asymptomatic) who has COVID-19. In other words, not often caught from surfaces. The most likely place to catch it? Bars. (see video).

We know that wearing masks prevents it. Infected people spread the disease before they feel sick so all should wear masks. Your mask protects me, mine protects you.

However, the human brain has a hard time grasping danger it hasn’t experienced yet. We humans don’t learn well from the history of others. And so …

“I think that wherever there’s wood to burn [people to infect], this fire’s going to burn – and right now we have a lot of susceptible people,” said Michael Osterholm, head of the University of Minnesota’s Center for Infectious Disease Research and Policy, on NBC.

“I don’t think we’re going to see one, two and three waves. I think we’re going to just see one very, very difficult forest fire of cases.”

— The Guardian: Half of U.S. states see coronavirus surge… 22 June 2020

UPDATES:

• Ongoing: Allegheny County records new case counts every day. The Public Source graph, above, is updated daily.
• 29 June 2020: Allegheny County bans on-site consumption of alcohol in bars and restaurants. This has been biggest source of the outbreak.
• 1 July 2020: PA mandates masks for everyone who leaves their home.
• 2 July 2020: Coronavirus cases more than double in 1 day: 233. Allegheny County closes bars, restaurants, casinos for one week.
• 10 July 2020: Indoor dining ban extended for 2 weeks.
• 14 July 2020: A one-day spike on 14 July follows a one-day lull due to delayed reporting. New cases on 13 and 14 July average to 200, which is the average daily rate for more than a week. 200 is not good, but it is not growing. Even better, the infection rate went down on 14 July.
• 15 August 2020: August looks better than July so far, but is still not as good as March-May.

(photos from Wikimedia Commons; click on the captions to see the originals)

A pink dogwood tree in Greenfield offers a left hand to passersby.

(photo by Richard St. John)

19 April 2020

Off the topic of nature and on the topic of science …

Face masks are in style now and in Pennsylvania they’re required, starting this evening 19 April 2020 at 8pm, for employees and customers at essential businesses. That includes grocery stores.

Since COVID-19 was first reported in the U.S. on 21 January 2020, the message about face masks has changed. Back then everyone asked, “What face mask will keep me safe?” Since then we’ve learned that staying safe is a community effort. If everyone maintains social distancing and wears a mask the disease can’t spread easily.

Here’s why.

Unprotected coughs really travel far — further than 6 feet — and they linger in the air. Click on the graphic to see a 3-D simulation of this in the New York Times.

Though a few states still haven’t issued stay-at-home orders — let alone mask-wearing — businesses understand the importance of masks. Walmart is requiring their employees to wear masks nationwide beginning tomorrow, 20 April 2020.

I’m happy to participate in this community effort as you can see in the photo at top. I made(*) my face mask from a cloth napkin + elastic earpieces + a plastic twist tie sewn into the top edge of the mask.

Your mask protects me. Mine protects you. Please wear one.

(*) Here’s a video on how to make the face mask plus the PDF of the pattern. I added this feature: I embedded a plastic-coated twist tie inside the top of the mask to hold the mask to my face so my glasses don’t fog as much.

(photo by Kate St. John, video from Wikimedia Commons, screenshot from the New York Times; click on the image to see the 3-D simulation)

p.s. How well are we doing on social distancing? Check out this Social Distancing Scoreboard that tracks trips and rates each state and county in the U.S.