IRA FLATOW: This is “Science Friday.” I’m Ira Flatow. A little bit later in the hour, biologist Craig Venter joins us to talk about his latest synthetic life form, Syn 3.0. It’s a bacterium with the smallest genome of any known self-replicating cell. Sounds exciting, we’ll talk about that, but first, California.

You know it’s still in the grips of its multi-year drought. Governor Jerry Brown signed an executive order that cut back water use by 25% in cities and towns. Restaurants only serve water upon request. Residents have been cutting down on shower times.

So why, oh, why, then, are reservoirs draining off their water? Here to tell us about these reservoir rules is Lauren Sommer. She’s the science and environment reporter at KQED in San Francisco, which is where she joins us from today. Welcome back.

LAUREN SOMMER: Hi, Ira.

IRA FLATOW: OK, so what’s with the state dumping water from reservoirs?

LAUREN SOMMER: Yeah, it sounds really bizarre, right? And the thing is these reservoirs aren’t even completely full. These are our biggest reservoirs. Obviously, we’re paying attention to every single storm that comes in and dumps water into them, but some of them are only, like, 60% full. And they’re having to release water and empty out, and it sounds really strange, right?

IRA FLATOW: You betcha.

LAUREN SOMMER: Well, there’s a good reason for that. When big storms hit here in California, you get a lot of water flowing out of the mountains, and these reservoirs need to have space to catch it. If you are too full and a big storm comes, you kind of risk overtopping the dam or maybe flooding people downstream. So it’s one of those things. The rule is there for safety reasons, but it feels weird to Californians who are having to conserve at home.

IRA FLATOW: This is an old rule, right? It goes back 100 years or more.

LAUREN SOMMER: Yep, and it’s the way water is kind of managed across the West. It’s kind of these very strict rules, but there are some folks and scientists here that are trying to change this. And they think it could be done better if you use weather forecasts. So instead of having these set rules about how empty you have to be, you could watch the weather forecast, and if a big storm comes through, you’re about to see it on the horizon, you could empty out the reservoir safely, create some space, just in case. But obviously the benefit is if the big storms don’t come in, you wouldn’t have released that water, and then maybe you would have it for later in the summer when you really need it.

IRA FLATOW: This sounds too logical.

LAUREN SOMMER: Yeah, and, you know, all of us know sometimes the weather forecasts are slightly off, and that’s a big deal for this kind of study. We have these big atmospheric river storms here in California. There’s kind of, like, this big stream of moisture that barrels across the Pacific and slams into California. A handful of these is actually most of our precipitation in a given year, but if you get it off just a little tiny bit, this strategy doesn’t quite work.

IRA FLATOW: Yes, and they’re trying to be overly cautious, is what you’re saying, because they know if they guess it wrong, it could be flooding and things like that that could be a disaster.

LAUREN SOMMER: Yeah, definitely.

IRA FLATOW: So they’re going to look into this a little more and see what happens.

LAUREN SOMMER: Yeah, if it works at a couple of reservoirs, they’ll probably expand it, but it has to work in those first few case studies.

IRA FLATOW: Yeah, all right, let’s move on to another story you’re working on. Researchers have pinpointed why some people are big risk takers. Does that mean, like, people who go gambling?

LAUREN SOMMER: Yeha, maybe I should ask you, Ira. If you walk into a Las Vegas casino, do you go straight to the high-stakes poker table or penny slots?

IRA FLATOW: I do. I do. I put my $5 down right on the high-stakes table.

LAUREN SOMMER: So according to these researchers, it probably has to do with what’s happening in one region of your brain. What they did is they set up an experiment with rats, and so there were these two levers that the rats could push. One was a nice, steady snack. It was guaranteed.

The other one would give them a really big snack, but it only happened every so often. It was a much riskier choice. And what they found is that the rats that were more conservative, that didn’t like taking risks, what was happening in their brains is that when they had to make that decision, their brain was sending them a signal reminding them of the loss of the previous choice they made. If they lost, there was a strong signal in one part of their brain. It involve dopamine, which is this neurochemical that’s important to emotion and thinking, and it was reminding them. Hey, that was pretty bad last time. You better play it safe.

But in the rats that really liked taking risks, they didn’t really get that signal as strong. Their brain wasn’t reminding them how painful it was last time, and they would just keep going back to that risky behavior. And so what the researchers did is they actually used light to manipulate the brain cells in these rats that liked taking risks, and they amped up that signal of the loss, of the pain. And they could make these rats that liked taking risks be more conservative just by altering this one signal.

IRA FLATOW: Wow, that’s not something they’re going to put in the drinks at the casinos any time soon, I don’t think.

LAUREN SOMMER: It would be bad for business I’m guessing, but what’s interesting is we know that there’s actually medications that can kind of, we think, interfere with this already. There’s a drug called Mirapex which is prescribed for some folks with Parkinson’s or restless legs syndrome, and there are people that are on that drug that some of them actually develop gambling problems because they think it’s interfering with this part of the brain.

IRA FLATOW: That’s very interesting. That is the serious part. Now, I understand there’s a killer out on the loose on the prairies.

LAUREN SOMMER: Yeah, this is a little bit of a dark story, just to warn you. It’s going to maybe alter your image of a very cute mammal, so are you prepared for this, hopefully?

IRA FLATOW: Of course.

LAUREN SOMMER: So these researchers were studying white-tailed prairie dogs in Western Colorado, and what they were noticing is that some of these prairie dogs seem to have serial killer tendencies. Yeah, they saw these adult prairie dogs running over, grabbing baby ground squirrels, which is a different species, and killing them and leaving their bodies behind. You know, run over, grab them, shake them, kill them, and leave them.

And this was a big surprise. Certainly, they weren’t expecting to see that without maybe them eating them or some other big benefit, but their hypothesis is just that these species, they eat some of the same grasses and plants. They’re herbivores, and so they found that some of these mother white-tailed prairie dogs, when they were killing lots of baby ground squirrels, it actually increased the likelihood that their own families would be successful. So maybe they are reducing the competition for a food source. That’s kind of the thought that these researchers have.

IRA FLATOW: Are they the only animals that do this kind of thing? Do we know of others?

LAUREN SOMMER: Yeah, I mean, it’s not that surprising in the carnivore world, like you can kind of picture, but those animals are kind of fighting for territory or for food resources. But it was really surprising for these researchers to see it in herbivores and not something you expect of a little mammal.

IRA FLATOW: Let’s talk about finding what– what is this burnt hot dog of the sea that you have uncovered?

LAUREN SOMMER: Yeah, these are sea cucumbers. You could think of them as maybe an animal that does not get a lot of respect. They are kind of these blobs. They move along the sea floor very slowly, not really charismatic, and this particular one really does look like a burnt hot dog. It’s kind of like a charred sausage color.

But a group of researchers was studying them off of the coast of Japan to figure out, how are these species doing? Is there enough genetic diversity because there’s actually a lot of fishing pressure on sea cucumbers? In some Asian countries, they are eaten, or they’re dried for medicinal purposes.

And they were finding that there was kind of alarmingly low levels of genetic diversity in this one population, and they are kind of raising the warning flag that, hey, you may not think they’re very cute. But sea cucumbers are actually really important to the marine ecosystem. They’re basically garbage men of the sea. They clean up all the detritus on the floor, so very important.

IRA FLATOW: Very important, and important stuff you always bring us, Lauren. Thank you very much for taking time to be with us today.

LAUREN SOMMER: Thanks, Ira.

IRA FLATOW: Wishing you more rain. Lauren Sommer is the science environment reporter at KQED in San Francisco. Now, it’s time to play good thing, bad thing.

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Because every story has a flip side, it’s becoming a regular story– warming temperatures, rising sea levels, shifting habitats. But how does that translate to your wine glass? Yeah, like wine? Joining me now to talk about the good and bad of climate change as it relates to wine is Elizabeth Wolkovich.

She’s an assistant professor of organismic and evolutionary biology based at Harvard University’s Arnold Arboretum in Boston, and she’s co-author of a paper out this week in the journal Nature Climate Change, looking at wine territories. Welcome to “Science Friday.”

ELIZABETH WOLKOVICH: Thanks, it’s nice to be here.

IRA FLATOW: You are welcome. The climate is shifting, making wine regions in France– what? They are being affected also?

ELIZABETH WOLKOVICH: Yes, so we looked at whether you can use the timing of the harvest dates of wine grapes going all the way back to the 1600s and see a couple of things. One, how is the timing of wine grape harvest changing? We also looked at some correlations with wine quality, and then we were fundamentally interested in using the records to ask how the climate system, itself, has shifted.

IRA FLATOW: And so what did you discover? There are longer periods of warm weather without being in drought, and that affects the wine?

ELIZABETH WOLKOVICH: Well, yes, so really the wine grapes are a sentinel for us to better understand the climate system in this paper. So what we found using these long term records– so these are all across France, from the Loire Valley, from Burgundy, from Bordeaux. Our colleagues collected these incredible records, going back to the 1300s, actually.

We put them together, and we said, what’s changed in what actually drives the timing of an early or a late harvest? And what we saw was that before 1980, a hot summer was usually an early harvest, and a hot summer was also a dry summer. And that makes sense from a climate perspective.

So to get a really hot summer back then, you needed dry soils to seed back with the air and warm it up and get really high temperatures in the 90s or 100s. But we see since 1980 in these harvest records is that a hot summer no longer has to be a dry summer. It could be a slightly wet summer, a humid summer, and all that’s driving the timing across France of wine grape harvest is just a hot summer. And a hot summer is no longer a dry summer, is the fundamental shift that we found.

IRA FLATOW: But isn’t that a good thing?

ELIZABETH WOLKOVICH: It’s not necessarily a good thing. It depends on what you’re talking about. So it’s may be a good thing right now for wine quality because high quality wines usually come from earlier harvests. Earlier harvests come from hotter summers, so we do get higher quality wines in the last 30 to 40 years. And that’s correlated with climate change.

That won’t last forever. And I think it’s a really bad thing because, you know, if you’ve ever spent a 90-degree day in a desert in California or a 90-degree day in the summer in Georgia, you know that a humid heat is a lot harder on people than a hot, dry heat. So we are expecting in Europe in the future, if we keep warming up the globe, that we will get more of these hot, humid summers, and those are actually really dangerous for people.

IRA FLATOW: Yeah, and as far as changing the wine-growing regions, will climate change change where the grapes are grown?

ELIZABETH WOLKOVICH: I think about that a lot, so there’s lots of projections that people have published over the last 10 years showing the great new wine growing regions of England and further north in Europe, where we haven’t really seen wine grapes for a very long time or perhaps forever, even though we have 1,000 years of records of where wine grapes have been grown. But I actually think there’s a lot of room for adaptation because wine grapes are actually incredibly climatically diverse. We have certain varieties like riesling. We grow riesling where it’s cold.

We grow pinot noir where it’s fairly cool. We grow cabernet sauvignon and Italian and Sicilian varieties where it’s really hot. If we change our varieties, I don’t think we have to change where we grow wine grapes.

IRA FLATOW: Elizabeth Wolkovich, assistant professor of organismic and evolutionary biology at Harvard. Thank you for taking time to be with us today.

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