Q: Is penis size or breast size important in our evolution or are they random occurrences that happen to be favored over time?
A: The size of our genitals and breasts are definitely important factors for our evolution. For example, human males have very large penises and testicles for our body size, compared to all other mammals. This is likely because when humans were evolving over many thousands of years, those males with larger penises tended to attract more mates (perhaps because this showed off their physical fitness) and men with larger testicles, and thus higher sperm counts, tended to get more women pregnant. It's likely that human males competed with each other through their sperm counts more so than most other mammals. This is because humans likely weren't monogamous maters. Human females most likely had sex with many different males and the males with the highest sperm counts would most likely be the "winners" when it came to getting females pregnant.
Human women also have quite large breasts for their body size, compared to other mammals. This is mainly because human babies require a LOT of nutrients when they are first born. Humans are born extremely prematurely compared to other mammals. For example, a chimpanzee baby can begin walking within a few weeks of being born, while human babies typically take about a year or more to begin walking. So, during that first year of development, human babies need a lot of crucial nutrients, proteins and fats to continue to develop their body and brains. This means they need large quantities of breast milk during this time. This made women with larger breasts more likely to have healthier offspring, thus passing on their genes more often than women with smaller breasts. However, there is also evidence that human females would typically share in breast-feeding duties for all of the babies within their tribe. So, a woman wouldn't be completely out of luck if she couldn't produce enough breast milk for her offspring, as other women in the tribe would probably help out. We still see this in modern hunter-gatherer tribes, such as those in the Amazon and in Papua New Guinea.
For more interesting info on the topic of human sexual evolution, check out the following links:
What human traits were evolved only for sexual attractiveness? by IO9
A Brief History of Human Sex by Live Science
Sexual Selection Continues to Shape Human Evolution, With Men Becoming More Attractive by Medical Daily
Q: I have recently read about women having orgasms based off nipple stimulation. Are titty orgasms a real thing?
A: I see this topic pop up on websites from time to time. It is true that some people can attain orgasm from nipple stimulation alone, but this is fairly rare. It's also true that some people can attain an orgasm from massaging the prostate or feet, or from working out, or from simply touching one's eyebrows. All of these are rare cases, but it shows that people can orgasm from just about anything if they are sexually excited enough. The orgasm reflex is still not completely understood by scientists, but orgasms seems to have a lot more to do with the brain than the genitals. So, for some, genital stimulation isn't necessary when it comes to having an orgasm.
However, having an orgasm from genital stimulation or non-genital stimulation results in the exact same feeling. Triggering the orgasm reflex will feel the same, no matter what triggers it. So, there is nothing you're "missing out" on by not experiencing a "nipple orgasm" or an "eyebrow orgasm." They're all just orgasms. So, no matter how you're having your orgasms, enjoy them! They're just as good as anyone else's.
Q: Should you permanently abstain from performing oral sex if you have herpes simplex-1 (cold sores), as the virus can become genital herpes if contracted through mouth-to-genital contact?
A: Herpes of the mouth, more commonly known as cold sores, is incredibly common. Studies show about 50 - 80% of adults in the U.S. test positive for this virus. So, if people with oral herpes couldn't perform oral sex, then virtually no one would be able to.
It's actually perfectly safe to perform oral sex if you have oral herpes, as long as you're not in the middle of an outbreak. If you have open sores (cold sores) on the mouth, then you should abstain from performing oral sex or touching people with your mouth in general, because this could spread the virus. However, if sores aren't present, then there is no way you could transmit the virus to anyone else. So, as long as you don't have open sores on your mouth, it's totally fine to perform oral sex.
Q: The other night my boyfriend asked me to give him a rimjob. I was disgusted with the thought of putting my mouth there. Is the technique sanitary? Can I get sick by doing it?
A: For one, if the thought of giving someone a rimjob (licking someone's anus) is disgusting to you, then you shouldn't feel pressured to do it. Any sexual experience should be one that's enjoyable for all people involved. If you would like to give it a try, though, rest assured that you will not get sick from doing it. Just make sure that your partner has showered beforehand.
It's always a good idea to shower at least an hour or two before having sex, no matter what you're doing in the bedroom. For example, if someone goes to the bathroom, the bacteria on their anus is likely to quickly spread to their genitals. Those areas of the body are close together and isn't separated by clothing, so any bacteria on the anus or genitals is likely to travel around. But, if someone has recently showered, then they have cleaned away this bacteria. Another benefit of showing before having sex is that it greatly reduces a woman's chance of developing vaginal or urinary tract infections afterward. Plus, you can make it fun by taking showers together!
Q: How do I get over a bad hookup? As in bad I mean incredibly awkward. I don’t necessarily have strong feelings for this person, but the event keeps playing over and over in my head and I’m not sure what to do.
A: If a person is "re-living" or obsessively thinking about a past sexual encounter, and especially if they're experiencing a lot of anxiety over this, then it may be that they felt coerced or forced to have sex. Even if a person didn't actively try to resist or say "no" during the sexual encounter, they may still have felt very uncomfortable during the situation. This can cause a person to feel fear, guilt, shame or general anxiety when they think back about that encounter. If this is the case, then that person should seek counseling to help them process what happened. Thankfully, UC Merced offers free counseling to all students. For more information, people can check out the counseling services website at counseling.ucmerced.edu.
Q: Can green tea extract have a negative affect my birth control pills?
A: A simple green tea extract would not cause birth control pills to stop working. However, certain tea products, such as Bootea "Teatox" can hinder the effects of birth control because they have a laxative effect. These products are usually used for dieting, but just cause a person to have diarrhea so that they lose water-weight. If someone is taking such products for a few days or more, it can lessen the absorption of other substances in their body, such as birth control and most other types of medication. These types of "diet" teas are not recommended by doctors, as they simply cause people to lose water weight, causing dehydration, and tend to hinder the absorption of medications and vitamins.
Other things that can cause birth control to stop working are...
If taking these other types of medications, birth control should still be taken regularly, but you should also use a secondary form of contraception (condoms) while taking this other medication. The same thing goes when using more long-acting birth control devices, such as an IUD or birth control implant.
Q: What am I supposed to do if I’m very sexually attracted to my professor?
A: It's fairly common for people to be sexually attracted to those who have power over them. For example, many people become sexually attracted to their teachers, bosses or therapists. This can come from seeing someone in power as being more confident and in-control than others, which can be a real turn-on. It could also be the case that someone you would normally find sexually attractive just happens to be in a position of power.
Regardless, it's not wise to act on these sexual feelings. When two people engage in a sexual relationship, they should be on equal footing. Having one person who has a lot of power over the other (such as being their teacher or boss) can create a coercive sexual relationship. For example, the person with power could pressure the other person to do things they wouldn't normally want to do. Or, the person with power could explicitly or implicitly offer things in exchange for sex, such as good grades or a promotion at work. This has become a hot topic of conversation with the current #metoo movement. This social movement has highlighted the many problematic things that can happen when people engage in a sexual relationship where there is this kind of lop-sided power dynamic.
The best thing to do in this type of situation is to acknowledge that you have these feelings, but just don't act on them. It's perfectly normal to have feelings like this, but it's also well within your control to not express them. There are many, many people you can have a sexual relationship with, wherein both of you have equal power in the relationship. Such relationships are bound to be much healthier and less problematic than trying to engage in a sexual relationship with someone who has disproportionate power over you and your life.
Q: Why do I last longer when I’m drunk?
A: Guys will typically take longer to ejaculate when they're intoxicated, because alcohol is a suppressant. Since it suppresses the nervous system during sex, the orgasm reflex can take longer to become active. Alcohol generally deadens the sensations involved in sex, which can decrease sexual arousal and even make it difficult to have an erection at all (commonly known as "whiskey dick").
In general, it's not a good idea to rely on alcohol to enhance your sex life. While it may be a temporary treatment for premature ejaculation, having too much to drink can seriously inhibit your sexual desire and performance. It can also cause people to make rash decisions, such as not using protection during sex or having sexual encounters that they later regret. In a recent study, 70% of people who had a sexual experience they later regretted said that alcohol was a factor.
If you want to have a more permanent solution to premature ejaculation, check out my earlier blog entry on that subject here.
Q: Why do we orgasm? What are their original purpose?
A: Animals (including humans) developed the orgasm reflex in order to motivate us to have sex and procreate. An orgasm is like a neurochemical fireworks show! It floods the brain with dopamine, which activates the pleasure centers of our brain. While the sensation of having an orgasm is relatively short-lived, it's akin to being "high." It leads to feelings of sensual pleasure and euphoria in ways that are very similar to drugs like heroin and cocaine. Of course, having orgasms is a much safer way of getting high than taking drugs. If we didn't have this great feeling from having sex, it's unlikely humans would have been motivated to have sex enough to keep our species going for as long as it has.
Q: What is the difference between estrogen, progesterone and testosterone? Which are found in males and which are found in females? Also what are their functions?
A: Estrogen, progesterone and testosterone are all hormones that are involved with gender development. Estrogen and progesterone are primarily thought of as female developmental hormones, while testosterone is a male developmental hormone (although all people have some level of each of these hormones in their body). Estrogen is primarily responsible for the feminization of the body, such as a woman's development during puberty (e.g., development of breasts, widening of hips, development of vulva and uterus), while progesterone is more involved in the process of ovulation and menstruation in women. Testosterone is primarily responsible for the masculinization of the body during male development (e.g., growing body hair, increasing muscle mass, development of penis and testicles).
Answers provided by Dr. Ross Avilla
Dr. Ross Avilla has been teaching Human Sexuality since 2013 and has a PhD in psychology from UC Davis. Dr. Avilla is not a clinician and all information and advice offered on this website is for educational purposes only.