• Question: why do we cry, when we get hurt? Why don't the oceans freeze? How do scientists know how to make a flu vaccine if viruses can be different every year?

    Asked by nipuniweerarathna to Claire, Joanna, Kapila, Renata, Suzanne on 19 Jun 2013.
    • Photo: Joanna Bryson

      Joanna Bryson answered on 19 Jun 2013:

      Could you try again, asking one question at a time?

    • Photo: Renata Medeiros

      Renata Medeiros answered on 19 Jun 2013:

      Oceans do freeze at the north and south poles but usually only a few meters at the surface get frozen. The oceans are massive and you will see for yourself that a little cube of water will freezer quicker than a full cup for instance. So to freeze the whole ocean it would need a lot of time at very low temperature. Even more so because salt water freezes at lower temperatures than normal water and because the oceans are very mobile, waters flow all the time so, even at the poles, warmer waters keep flowing in. Furthermore, once the surface freezes, that frozen layer helps to keep the water below a bit warmer (the best way to keep warm in the snow is to dig a hole and lay on it). All these reasons together prevent our oceans of freezing completely, which would make life on the ocean pretty much impossible.
      Could give it a go about the vaccines but it really isn’t my field so I rather not risk saying something stupid. I also don’t know why we cry but it is certainly an interesting question because many other animals can produce tears but they don’t really cry with tears when in pain. I will look it up myself! Thanks for asking 🙂

    • Photo: Claire El Mouden

      Claire El Mouden answered on 26 Jun 2013:

      I’ll answer you question about crying. Great question…because the simple answer is ‘we don’t really know!’…see how easy it is to find cutting-edge scientific questions? 🙂

      Humans are unique, because although animals make tears to keep their eyes clean, and many animals yelp or cry out when they’re in pain, humans are the only species that shed tears for emotional reasons and actually cry and sob. Therefore, crying is an adaptation (natural selection favoured people who cry), so it must have conferred some benefit. What though?

      One theory is that crying may have evolved as a kind of signal — a signal that was valuable because it could only be picked up by those closest to us who could actually see our tears. Predators or other people would not be able to see we were feeling vulnerable. Tears let people who are physically close to us know we are not OK, and moreover, when we see someone cry, we tend to share the emotion. So I think crying evolved as a form of social communication.

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