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"Older brother effect" may help explain homosexuality in males.

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"Older brother effect" may help explain homosexuality in males.

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For decades, scientists have been trying to figure out which biological factors determine sexuality. One of the more inexplicable discoveries in this arena is that homosexuality is more common in men who have older brothers, known as the "older brother effect". Up until now, it's been unclear why that is.

New research from Brock University in Canada suggests that women who give birth to boys multiple times progressively build up antibodies that will affect their future sons in utero. The researchers argue that these antibodies, formed in response to proteins present in male brains, may lead to changes in brain development that influence sexual orientation.

"It seems that some women during their first male pregnancy, or just after their first male birth, begin to detect this foreign substance (the NLGN4Y protein) and start to develop an immune response. And then later, with further male pregnancies, the high levels of antibodies directed toward this substance may change brain development in these later born males," says lead researcher Tony Bogaert in a media release.

While the study has yet to be replicated by another research team, it suggests that the older brother effect is rooted in prenatal factors. In other words, this is yet more evidence that sexual orientation has a biological basis, a point that has long been contested by anti-gay types.

"The implications of this study, especially if and when it is replicated by an independent team, are profound," explains Bogaert.

"Along with more deeply understanding the exact origin of the older brother effect, it helps solidify the idea that, at least in men, there's a strong biological basis to sexual orientation.

"This is the culmination of more than 20 years of research where we started looking at the older brother, or fraternal birth order, effect. The current study adds to the growing scientific consensus that homosexuality is not a choice, but rather an innate predisposition."

There's no single factor determining whether a person is gay or not, but research like this continues to support the theory that sexual orientation is at the very least influenced by biological factors. Considering that anti-gay groups still push the notion that being gay is a choice that can be fixed with harmful conversion therapy and the like, this area of research is truly valuable.
This story has been updated.

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New Research Sheds Light on the Biological Factors That Influence Sexuality

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Shutterstock For decades, scientists have been trying to figure out which biological factors determine sexuality. One of the more inexplicable discoveries in this arena is that homosexuality is more common in men who have older brothers, known as the "older brother effect". Up until now, it's been unclear why that is.

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Hi guys, this is my Spider Silk research report from my study last year. I'll post it here in case anyone wants to take a look. =-)

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By: Parker Broadnax, Logan Faucett, and Natalie Canterbury
Abstract
To date, spider silk is one of the world's strongest natural fiber. It possesses outstanding feats of strength, all while staying extremely lightweight and flexible. These qualities are unmatched by other fibers, such as cotton or nylon and ounce per ounce is stronger than steel, giving it a wide variety of industrial applications. It's value increases furthermore, since it is a renewable resource. The potential to utilise this resource is declining since spiders habit in Costa Rica is being threatened by deforestation. Many companies also use abusive methods to obtain this material, including pinning down the spider and forcibly pulling its silk. This paper studies the silk of Nephila clavipes in Costa Rica The goal of the Forman Spider Silk Team is to further researching humane practices of spider silk extraction and to look at the strength of the silk when combined with other fibers. This study explores the change of spider silk's strength when combined with wool, kevlar, hemp, nylon, cotton, and nylon monofilament.
Introduction
The 2017 Spider Silk team was led by Logan Faucett, Parker Broadnax, and Natalie Canterbury. from left to right Parker, Natalie, Logan, Wendy Welshans) The Spider Silk team is entering its twenty first year of operation. Past research has included the economics of harvesting spider silk, designing enclosures for the spiders, and collecting/testing spider silk mega samples. The objective for this project is to incentivise spider silk as a valuable resource, discourage the destruction of the spider's habitat through deforestation. The spider being looked at in this project is the Nephila clavipes, more commonly known as the Golden Orb Weaver spider. Nephila clavipes silk is one of the strongest of the orb weavers spiders; however, they are one of the few with significantly strong silk that live together in colonies. These traits makes them an ideal choice for farming, and a very promising renewable resource.

The silk is extracted using the "silkinator," a patented spider silk technology. The silkinator in past years has been a metal disk, with eight spokes welded around the circumference. The wheel is mounted onto a metal box, approximately 16 cm^3. A thin metal rod runs through the wheel and the box, enabling technicians to spin the wheel by cranking a handle. This year a new wheel was developed, a wheel that can collapse to allow the operators to easily remove the silk for testing. The spider's silk is attached onto the wheel, and it collects around the wheel as it turns. The specific silk the team is harvesting comes from the major ampullate gland, also known as dragline silk. This dragline silk is the strongest of all the spider's natural silk glands (Hayashi, 2010).

The Forman Spider Silk team is one of the few programs that practices the humane extraction of spider silk. Many other companies use questionable practices. A live spider is taped or even pinned to a board, while it's silk is harvested (Adams, 2013). The consideration for the well being of the spider does not take away from any aspects of the efficiency or yield of silk collection.

Patents found in , and represent Forman school's first patents regarding the manual and mechanical extraction of spider silk. The patent found in represents a healthy and renewable structure to farm Nephila's for their silk.
Methods
The first step to farming is the mapping process the spider enclosure. Keeping a record of how many spiders there are, where they have constructed webs, and tracking which spiders are silked when helps to ensure that the same spiders are not over silked. Mapping also records which spiders are fed. The mapping process removes the possibility of silking a spider more than once in any given day or over taxing a spider's health.

At the time a session starts environmental factors are recorded using a portable weather station. The factors including time of day, collection date, temperature, dew point, barometric pressure, and wind speed. All are entered into a data table with specifications of the silk from that session. This will be used to look at correlations between strength of silk and whether or not certain conditions affected the silk.

Spiders live on their webs when they are not being silked and after a session is complete they are returned to the same web. In order to safely care for the spiders and their webs the use of a method that is described as the Welshans cage method is employed.

The Welshans cage method is the process of removing the spider from their web without harming the spider and damaging the web. The handler hovers their hand in front of the web, and going down ward stopping at the spider to corral the spider into their hand. It is the spider's instinct to travel upwards and this is used as an advantage. It is extremely important not to touch the web. The spider will crawl into the open palmed hand. Once this happens the handler will close their hand a small amount very gingerly as to simply cage the spider.

After using this method to pick up the spider they are brought over to the station to begin silking. The handler will support the spider on the back of their hands, and once the spider has lain a sticky disc it will be plucked from the handler's hand, and placed onto the wheel. Once the silk is around the wheel, the operator will begin collecting the silk. The amount of silk and the rate of silking is measured by a bike odometer.

Using this odometer data can be collected regarding rotations, speed of rotation, and then calculate collective feet gathered. Using (r = no. of revolutions) Amount of silk in feet = r x 10/12" to convert rotations to feet. The bike counter also needs to be set to the number 1500 to take into account the smaller wheel as opposed to that of one from an actual bicycle.

Once 250 rotations has been reached the spider is returned to its web and the operator then does one of two things. Either an operator combines the silk with one of six fibers that are being looked at or, starts to remove the silk for testing without being spliced. To remove silk with the new collapsible wheel it is first pushed together within ¼ an inch using two probes carefully, as to maintain the quality. Following this the spinner then unscrews the pegs to allow them to collapse releasing the silk to be collected on these two probes. These probes with the silk around them are taken over to the field tensile lab to be tested.

To combine the silk with fibers for testing, the operator starts from when silking has ended and spider has been returned to its web. From this step the silk is bunched together tightly on the wheel, taking note to maintain the quality of the silk. Fibers are broken down proportionally as shown in Each fiber is cut at 22 inches long and then applied to the silk.

Table 1. Thickness for fibers tested with spider silk
(table 1)
With this fiber in one hand the operator begins to splice the fiber with the silk. Starting from the inside between two pegs it is twisted three times between each peg. Taking care full note not to stress the silk nor the fiber. After every three twist it is brought over once more in the same fashion yet making sure that it goes over the peg as to not create space between the silk and the fiber that would cause problems in the future. This step is repeated eight times for a total of 24 twist altogether. Then taking the two ends of the fiber the surgeon's knot shown in is tied tightly as to have no excess space between the fiber and silk. From this point it is removed in the same fashion as before, by releasing the screws allowing the pegs to slide inward and taking two probes to transfer the spliced fiber and silk to our field testing tensile lab.

The Vernier Wireless dynamics sensor system (tensile lab), as stated is used to measure tensile strength, shown in Newtons (N). The silk is pulled by an actuator, at a constant speed giving us consistent data representative of the silks strength. This data is collected from the tensile lab and shown on a graph as force (N) over time (s). Example of Graph Shown is a graph of 250 rotations of pure spider silk with a reading of 19.8N

Graph of spider silk, measured in force (N) over time (s)

This is an example of a sample of 250 strands of golden colored silk.
Equipment Results
Over the course of fourteen days, the team collected silk from forty five different Nephila clavipes spiders. In the twenty five trials that tested spider silk on its own, on average the strength of the silk measured 6.21 N. Within the twenty-five trials with only spider silk, there was a standard deviation of 4.873. The silk of the Nephila clavipes was spliced with six different types of fibers: hemp, nylon monofilament, kevlar, wool and cotton. The control value of hemp measured 7.44 N and increased in strength by 321 percent once combined with spider silk reading 31.29 N. The control value of kevlar measured 5.58 N and increased in strength by 427.5percent when combined with the silk, measuring 29.429 N. The control value of nylon monofilament measured 16.4 N and increased by 7.83percent once combined with silk which measured 17.69 N. The control value of wool measured 4.57 N and increased by 229.76 percent once combined with the silk at 15.07 N. The control value of cotton measured 9.3 N and increased by 32.15 percent in strength once combined with the silk measuring 12.29 N. The control value for nylon measured 9.78 N and increased by -7.9 percent in strength once combined with the silk measuring 9.007 N. All of these measurements can also be seen in table 2, 3 and 4 as well as figure 4. Though these percent's show interesting results, more sampling must be done to make any final conclusions.

Below the tables represent the strength of the fibers before splicing.

Control Strengths of Each Fiber in Newtons

Strength of Native Non-spliced Spider Silk Samples Tested

Strength of Spider Silk Combined with Fibers
Discussion
In the original hypothesis, it was predicted that the spider silk would increase the strength of all of the fibers equally. In this theory, the high modulus fibers would result in the strongest fiber when combined with the spider silk. However once the experiment was conducted, the spider silk proved to increase the strength of each fiber unequally. Nylon Monofilament was the strongest fiber on its own (16.4 N), even though it had one of the smallest amounts of growth (7.83 percent). On the other hand, hemp had the second largest growth (321 percent) despite being one the weaker fibers. It is predicted that this splice is as strong as it is do to the silk's gossamer qualities mixing with hemp's coarse and fibrous qualities. The increase in percent growth of tensile strength has a direct correlation to fibers with a rough and fibrous texture. The silk had better enhancement properties when it had a more opportunites to hook onto the fibers' surface, making nylon monofilament a weak candidate. As seen in , hemp has an extremely dense and bristly structure to ensnare the silk. For future research, combining spider silk with other fibrous materials like hemp and kevlar would potentially yield some significantly strong results. In addition, fibers with textures similar to hemp, such as kenaf, would make promising candidates for future spider silk splicing trials.

This year's findings have led to a promising future for spider silk. The team has communicated with Alex Newbery, an alumnus of the project from 2005. Alex is currently finishing his M.D. as an orthopedic surgeon at Massachusetts Medical School he is exploring the use of spider silk in the orthopedic field. He is looking at the possibility of using spider silk to rebuild flexor tendons in the hand. Spider silk's high tensile strength along with its antimicrobial, hypoallergenic, and biodegradable properties (Römer & Scheibel,2008), makes it perfect for a variety of orthopedic applications. He estimates that it will perform significantly better than the material that is currently used today. The team's tests on the interactions between spider silk and nylon monofilament will contribute to Alex's research.
References
Adams, T. (2013, January 12). Fritz Vollrath: 'Who wouldn't want to work with spiders?'. . Retrieved from The Guardian https://www.theguardian.com/science/2013/jan/12/fritz-vollrath-spiders-tim-adams

Arenas, J. P., & Crocker, M. (2010). Recent Trends in Porous Sound-Absorbing Materials. (7), 12-17. Retrieved from Sound & Vibration , https://www.researchgate.net/publication/272151761_Recent_Trends_in_Porous_Sound-Absorbing_Materials

Ebbert, D., & Dietrich, W. (2016, May). Spider Silk: A Mega Year with Mega Findings .

Hayashi, C. (2010, February). [Video file]. Retrieved from The Magnificence of Spider Silk https://www.ted.com/talks/cheryl_hayashi_the_magnificence_of_spider_silk

Römer, L., & Scheibel, T. (2008, November). The elaborate structure of spider silk. (4), 154-161. Retrieved from The elaborate structure of spider silk , https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2658765/#R67
Acknowledgments
A special thanks to:

William Dietrich
Authorship
Robert Logan Faucett

Parker Durrah Brodnax

Natalie Rose Canterbury

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The Effect of Combining Nephila clavipes Silk to find Correlations between Splicing with Fibers By: Parker Broadnax, Logan Faucett, and Natalie Canterbury Abstract To date, spider silk is one of the world's strongest natural fiber. It possesses outstanding feats of strength, all while staying extremely lightweight and flexible.

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Proceedings of the Royal Society of London B: Biological Sciences

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The evolution of tail weaponization in amniotes

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Weaponry, for the purpose of intraspecific combat or predator defence, is one of the most widespread animal adaptations, yet the selective pressures and constraints governing its phenotypic diversity and skeletal regionalization are not well understood. Here, we investigate the evolution of tail weaponry in amniotes, a rare form of weaponry that nonetheless evolved independently among a broad spectrum of life including mammals, turtles and dinosaurs.

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Antisocial bees point to genetic origins of autism.

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Antisocial bees point to genetic origins of autism.

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Sociobiology is still controversial (and relevant!)

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Antisocial bees point to autism’s ancient genetic origins _ Cosmos