Male contraception hasn't changed much since the condom was invented over 5,000 years ago. You can blame biology.

The condom was invented more than 5,000 years ago. While it's made some strides since then, men are still left with few options for birth control, besides a vasectomy.
It's not due to a lack of interest, but a lack of funding for research — and biology.
Men produce millions of sperm each day. Even if that count is reduced by 90%, they could still be fertile.
There are new methods coming, but experts say it will be years, if not decades, before they hit the market.
Visit BusinessInsider.com for more stories.

Following is a transcript of the video.

Did you know the condom is over 5,000 years old? That's right, some of the first forms of birth control date back to around 3,000 BC, and while the condom has made some strides since the Bronze Age, men still don't have a much better option all these millennia later. Besides a vasectomy. Especially compared to the pills, IUDs, and implants available to women today. So why don't we have birth control for men? In 2002, researchers asked more than 9,000 men across four continents whether they'd be willing to use contraception capable of preventing sperm production. Over half said yes. So the problem isn't lack of interest, it's partly human biology. Women ovulate just one or two eggs each month. Men, on the other hand, produce sperm daily, and it's not just one or two.

There's literally hundreds of millions of sperm produced each day, so because there's so many sperm produced, actually, you can reduce your sperm number over 90% and still be completely fertile. Narrator: To reach infertility, a man's sperm count needs to be somewhere around 1 to 10 million per milliliter, but getting there is near impossible, at least without side effects. That's because sperm count is tied to the production of testosterone. In the past, researchers tried decreasing testosterone in an effort to decrease sperm count.

The problem is you don't have any libido, you have very little testosterone to act on other tissues and so forth, and so the side effects were so dramatic that it really wasn't ever going to be a contraceptive pill. Narrator: Scientists also tried using different compounds that attack the cells that produce sperm. But again, biology got in the way. Germ cells, as they're called, developed inside a fortress-like structure within the testes.

So literally, nothing can get through it. There's been a lot of small molecule studies to try and actually attack the germ cell to stop it from working. Literally, I can think of 10 or 15 different compounds that actually have been developed to do that, but they don't work because of that barrier. Narrator: But the complex male anatomy isn't the only problem. It's also funding or lack thereof. In 2002, two big pharmaceutical companies took interest in male contraception, Schering and Organon. And together they funded a large clinical trial on a hormone-based contraceptive, offering hope that a pill backed by Big Pharma might be on the horizon.

Then these two companies became, as you know, acquired by bigger company, and then even bigger company, so now they are merged in huge companies, and women's health is still a priority in many of the companies, but men's health became part of the general matter of health. And therefore, the development of contraception becomes a really very low priority. Narrator: According to Dr. Wang, male contraception was also too risky for Big Pharma at the time. The long-term side effects were unknown. Companies were concerned that women might not trust it, and despite the survey results, it was unclear whether men would actually use a hormone-based contraception. Today, the limited funding comes mostly from government agencies like the National Institutes of Health. But there are in fact some promising lines of research. Dr. Wang is working on a gel that can lower testosterone where it matters, in the testes where sperm is produced, while keeping testosterone levels normal elsewhere. That means low sperm count and, more importantly, no major side effects.

We have preliminary studies to show that if we give the gel and if the man applies the gel, 90% of the men will reach the level that you talk about, 1 million per mil.

And Skinner is pursuing a new approach, shutting down Sertoli cells, which are a part of that impenetrable barrier that houses germ cells.

So if you shut down the Sertoli cell, then you shut down the sperm production. Narrator: But perhaps most promising is a sort of reversible vasectomy that's in the works.

So they have this ability to inject this gel into what's called the vas deferens, and it makes this plug, so then essentially it does the same thing, but you're not cutting it. Then believe it or not, you can actually inject this chemical mixture, which will dissolve the plug, and so then you can get your fertility back. Narrator: But as promising as these approaches may be, they're still years, if not decades, out, Skinner says. And without more funding, some of them may never hit the market. So at least for now, men are left with few options. Irreversible vasectomies, pulling out , and that slightly updated Bronze Age invention.

Join the conversation about this story »