Its classic Biology 101: A mother has two sex chromosomes, X and X, and a father has an X and a Y, and the combination in a new embryo determines the sex. So, statistically, there should be an equal number of newborn male and female babies in the world. But, in reality, there are slightly more boys than girls. According to World Bank data, the global sex ratio at birth (SRB) of males to females in a population stands at around 107:100.
In order to offer some explanations for this phenomenon, a team of scientists did a large-scale study, attempting to find associations between various societal and environmental factors for shifts in the SRB in both directions. They found that factors including chemical pollutants, food deserts, and crowdedness led to slight changes in SRB. They note these are only correlations, so more work has to be done to assess direct cause and effect, and to explain why it might be happening, biologically.
Sex is determined at conception, when parents chromosomes pair up in random fashion. So, its likely later, during pregnancy, when environmental factors could shape the fate of an embryo, says Andrey Rzhetsky, professor of medicine and human genetics at the University of Chicago, and one of the studys authors. Whether more male or female embryos die during gestationessentially, via miscarriagesprobably determines the SRB. Under different circumstances, embryos of one sex are dying more often, skewing the SRB one way or the other. Sex ratio is determined by the environment because some embryos are dying spontaneously, he says. And we dont know why.
Using national data, the team studied the entire Swedish population (about 9 million) over the course of 30 years, and half the U.S. population (about 150 million) over the course of 8. They tested 100 hypotheses, including environmental factors like the presence of mercury in water, lead in land, and air pollution particulates; and social factors, such as traffic, high renter-occupancy level, and negative food-related business, an EPA term denoting an areas higher prevalence of unhealthy eateries like fast-food restaurants, convenience stores, and pretzel trucks.
They found that some of the factors produced more male babies born compared to females, while others produced the opposite. For instance, pollutants like mercury in water and fine particulate matter in air were associated with more male babies, whereas lead in land correlated with more female babies. Extreme drought and traffic fatality rate were associated with males; high renter-occupancy level and fast-food prevalence with females. Within some groups tested, the researchers registered up to a 4% change in the SRB, which would equate to about 40,000 babies in a population of 1 million.
Rzhetsky notes that these are simply associations, not causes and effects. Still, he argues that they are more than coincidences, given that sex ratio consistently varies across the U.S. Without further work, he wont speculate much as to why, biologically, these changes happen. He says, its established that stress factors can cause termination, so its possible that a biological mechanism terminates a pregnancy under unfavorable factors, when high stress hormone levels are detected, to try and keep a mother safe.
Hes also open to a possibility, as other scientists have suggested, that the stress factors skew survival of gametes (the cells that come together to form an embryo) of one sex more than another, meaning that the environmental effects are happening before gestation. But, because the chromosome pairing is random, he thinks the miscarriage theory is more plausible. To ascertain more, and concrete, explanations, he recommends further work, probably with lab mice, or experiments with human cell tissuesboth embryos and gametes.
A notable, and perhaps surprising, finding from the study was that some factors, which scientists long thought would be prime drivers of sex ratio change, including changes of the seasons and of ambient temperatures, were not associated with SRB shifts. Nor were stressors such as violent crime and unemployment. But, Absence of proof is not proof of absence, Rzhetsky says, again recommending further study.
Here is the original post:
Could pollution, traffic, and fast food be affecting how many babies of each sex are born? - Fast Company
- Copy number variation of the restorer Rf4 underlies human selection ... - Nature.com - November 15th, 2023 [November 15th, 2023]
- NYU Langone Health in the NewsThursday, November 9, 2023 - NYU Langone Health - November 15th, 2023 [November 15th, 2023]
- Eugenics: Plaguing scientific community with dark history | Opinion ... - The Arkansas Traveler - November 15th, 2023 [November 15th, 2023]
- Cranberries can bounce, float and pollinate themselves: The saucy ... - Japan Today - November 15th, 2023 [November 15th, 2023]
- Government Housing Assistance Linked to Increased Cancer ... - HealthDay - November 15th, 2023 [November 15th, 2023]
- Rate of New Lung Cancer Cases Has Decreased Over Last Five Years - HealthDay - November 15th, 2023 [November 15th, 2023]
- Clinically relevant antibiotic resistance genes are linked to a limited ... - Nature.com - November 15th, 2023 [November 15th, 2023]
- Disparities in Guideline-Concordant Care Found for Black CRC ... - HealthDay - November 15th, 2023 [November 15th, 2023]
- Mathematician Heather Harrington is new director at the Max Planck ... - EurekAlert - November 15th, 2023 [November 15th, 2023]
- New study finds genetic testing can effectively identify patients with ... - EurekAlert - November 15th, 2023 [November 15th, 2023]
- STK11 loss leads to YAP1-mediated transcriptional activation in ... - Nature.com - November 15th, 2023 [November 15th, 2023]
- CRISPR-broad: combined design of multi-targeting gRNAs and ... - Nature.com - November 15th, 2023 [November 15th, 2023]
- Master regulator of the dark genome greatly improves cancer T-cell ... - Science Daily - November 15th, 2023 [November 15th, 2023]
- Omega Therapeutics Showcases Bidirectional and Multiplexed ... - BioSpace - November 15th, 2023 [November 15th, 2023]
- Today is International 15q Day - ASBMB Today - November 15th, 2023 [November 15th, 2023]
- Evolution of taste: Sharks were already able to perceive bitter ... - EurekAlert - November 15th, 2023 [November 15th, 2023]
- Stanford Scientists Uncover New Indicators of Health, Disease, and ... - SciTechDaily - October 16th, 2023 [October 16th, 2023]
- NHGRI Director Eric Green elected to the National Academy of ... - National Human Genome Research Institute - October 16th, 2023 [October 16th, 2023]
- Monkey survives for two years after gene-edited pig-kidney transplant - Nature.com - October 16th, 2023 [October 16th, 2023]
- Opinion: Interest in RNA Editing Accelerates as Therapies Approach ... - BioSpace - October 16th, 2023 [October 16th, 2023]
- Regulation of dermal fibroblasts by human neutrophil peptides ... - Nature.com - October 16th, 2023 [October 16th, 2023]
- Consistent effects of the genetics of happiness across the lifespan ... - Nature.com - October 16th, 2023 [October 16th, 2023]
- Storytelling through the looking glass of genetics The Stute - The Stute - October 16th, 2023 [October 16th, 2023]
- Pet dogs shed light on human health, researchers say - UPI News - October 16th, 2023 [October 16th, 2023]
- Native microbiome dominates over host factors in shaping the ... - Nature.com - October 16th, 2023 [October 16th, 2023]
- Illinois-led project to sequence soybean genomes, improve future ... - Herald-Whig - October 16th, 2023 [October 16th, 2023]
- Unrealized targets in the discovery of antibiotics for Gram-negative ... - Nature.com - October 16th, 2023 [October 16th, 2023]
- How Biotech And AI Are Transforming The Human - Noema Magazine - October 16th, 2023 [October 16th, 2023]
- The Many Lives of Alexandria Forbes - BioSpace - October 16th, 2023 [October 16th, 2023]
- CEP20 promotes invasion and metastasis of non-small cell lung ... - Nature.com - October 16th, 2023 [October 16th, 2023]
- Genotyping, sequencing and analysis of 140,000 adults from Mexico ... - Nature.com - October 16th, 2023 [October 16th, 2023]
- The role and impact of alternative polyadenylation and miRNA ... - Nature.com - October 16th, 2023 [October 16th, 2023]
- Human - Simple English Wikipedia, the free encyclopedia - January 30th, 2023 [January 30th, 2023]
- Deep Dive Ties Together Dog Genetics, Brain Physiology and Behavior to Explain Why Collies Are Different from Terriers - Scientific American - December 12th, 2022 [December 12th, 2022]
- How oxytocin drives connections of newly integrated adult-born neurons: Research - Hindustan Times - December 12th, 2022 [December 12th, 2022]
- Alzheimer's Disease Genetics Fact Sheet - National Institute on Aging - December 2nd, 2022 [December 2nd, 2022]
- Human genetic clustering - Wikipedia - November 23rd, 2022 [November 23rd, 2022]
- Human Genome Project Fact Sheet - November 23rd, 2022 [November 23rd, 2022]
- Abstracts | International Congress of Human Genetics 2023 - November 23rd, 2022 [November 23rd, 2022]
- Ancient DNA and Neanderthals | The Smithsonian Institution's Human ... - November 16th, 2022 [November 16th, 2022]
- Biological Influences on Human Behavior: Genetics & Environment - November 16th, 2022 [November 16th, 2022]
- Fluent BioSciences showcasing breakthrough solutions to enable unprecedented scale, cost-efficiency and access for single-cell RNA sequencing at the... - October 28th, 2022 [October 28th, 2022]
- Human behaviour genetics - Wikipedia - October 23rd, 2022 [October 23rd, 2022]
- Nucleome Therapeutics raises oversubscribed 37.5 million Series A financing to decode the dark matter of the human genome and deliver first-in-class... - October 19th, 2022 [October 19th, 2022]
- Gladstone data scientist elected to the National Academy of Medicine - EurekAlert - October 19th, 2022 [October 19th, 2022]
- Ocugen to Host R&D Day in New York City on Tuesday, November 1, 2022 - Yahoo Finance - October 19th, 2022 [October 19th, 2022]
- Pharmacy researcher earns $2.3 million NIH award to study opioid addiction - EurekAlert - October 19th, 2022 [October 19th, 2022]
- Study shows age often plays a bigger role than genetics in gene expression and susceptibility to disease - Anti Aging News - October 19th, 2022 [October 19th, 2022]
- CSRWire - Direct Relief, Amgen and C/Can Team Up To Improve Access to Breast Cancer Diagnostics and Treatment in Paraguay - CSRwire.com - October 19th, 2022 [October 19th, 2022]
- Maze Therapeutics Appoints Harold Bernstein, M.D., Ph.D., as President, Research and Development and Chief Medical Officer - Business Wire - October 19th, 2022 [October 19th, 2022]
- New Rare Disease Therapy Effectively Lowers Plasma Phe in Patients with PKU - MD Magazine - October 19th, 2022 [October 19th, 2022]
- GSK : announces expanded collaboration with Tempus in precision medicine to accelerate R&D - Marketscreener.com - October 19th, 2022 [October 19th, 2022]
- Famous Scientific Discoveries That Changed the Course of History - 24/7 Wall St. - October 19th, 2022 [October 19th, 2022]
- Construction workers seek fulfilment of their demands - Star of Mysore - October 19th, 2022 [October 19th, 2022]
- Genetics | The Smithsonian Institution's Human Origins Program - October 13th, 2022 [October 13th, 2022]
- Genetics - Wikipedia - October 13th, 2022 [October 13th, 2022]
- Study looking at human genetics and Covid vaccine immune responses - Science Media Centre - October 13th, 2022 [October 13th, 2022]
- ASHG 2022 in Los Angeles brings together researchers from around the world to advance discoveries in genetics, genomics research - EurekAlert - October 13th, 2022 [October 13th, 2022]
- Maze Therapeutics Appoints Harold Bernstein, M.D., Ph.D., as President, Research and Development and Chief Medical Officer - Yahoo Finance - October 13th, 2022 [October 13th, 2022]
- The Age of the Pangenome Dawns - DNA Science - PLOS - October 13th, 2022 [October 13th, 2022]
- Influence of the microbiome, diet and genetics on inter-individual variation in the human plasma metabolome - Nature.com - October 13th, 2022 [October 13th, 2022]
- Genome editing technologies: final conclusions of the re-examination of Article 13 of the Oviedo Convention - Council of Europe - October 13th, 2022 [October 13th, 2022]
- Global Biobank Meta-analysis Initiative making genome-wide association studies more diverse and representative - EurekAlert - October 13th, 2022 [October 13th, 2022]
- New NHS genetic testing service could save thousands of children in England - The Guardian - October 13th, 2022 [October 13th, 2022]
- Covid protection may be boosted by genes, study shows - Yahoo News Australia - October 13th, 2022 [October 13th, 2022]
- Genomics in Cancer Care Market is estimated to be US$ 72.61 billion by 2032 with a CAGR of 16.3% during the forecast period 2032 - By PMI -... - October 13th, 2022 [October 13th, 2022]
- Identification of hub genes and candidate herbal treatment in obesity through integrated bioinformatic analysis and reverse network pharmacology |... - October 13th, 2022 [October 13th, 2022]
- Our *Homo sapiens* ancestors shared the world with Neanderthals, Denisovans and other types of humans whose DNA lives on in our genes -... - October 8th, 2022 [October 8th, 2022]
- Blue Eyed People Have a Single Ancestor | History of Yesterday - History of Yesterday - October 6th, 2022 [October 6th, 2022]
- Heart infection could be cause of death of Polish, US hero - ABC News - October 6th, 2022 [October 6th, 2022]
- 23andMe Announces Trials-in-Progress Poster Presentation on 23ME-00610, An Investigational Antibody Targeting CD200R1, at The Society for... - October 6th, 2022 [October 6th, 2022]
- The Genetic Drivers Of Longevity In Mice, Humans And Worms - Science 2.0 - October 6th, 2022 [October 6th, 2022]
- ANGPTL7, a therapeutic target for increased intraocular pressure and glaucoma | Communications Biology - Nature.com - October 6th, 2022 [October 6th, 2022]
- 'Neanderthal Man' Nobel Prize winner Svante Pbo revolutionized anthropology. Here is a look back at his groundbreaking 2014 memoir - Genetic Literacy... - October 6th, 2022 [October 6th, 2022]
- Understanding Human Genetic Variation - NCBI Bookshelf - September 14th, 2022 [September 14th, 2022]
- Genetics - National Institute of General Medical Sciences (NIGMS) - September 14th, 2022 [September 14th, 2022]
- People with ME invited to take part in major genetic study - The Independent - September 14th, 2022 [September 14th, 2022]
- Ketamine Promising for Rare Condition Linked to Autism - Medscape - September 14th, 2022 [September 14th, 2022]
- How a small, unassuming fish helps reveal gene adaptations - University of Wisconsin-Madison - September 14th, 2022 [September 14th, 2022]
- How Nutrigenomics Explores Links Between Nutrition And Genes - Health Digest - September 14th, 2022 [September 14th, 2022]