Shadowing Practice: The Evolution of Human Skin Colour | BBC Earth Science - Learn English Speaking with Video

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34 משפטים

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This map shows how UV varies across the globe.

Throughout Africa there are these very high levels, but the levels taper off dramatically as we begin to get into Western Europe or Eastern Asia.

And in places with less UV, high levels of melanin created a problem.

There are some wavelengths of UV that are actually essential to our health, that promote the production of vitamin D in our skin.

We need vitamin D for a strong immune system and healthy bones.

With less exposure to the sun, our ancestors couldn't make enough of it.

To survive in these new lands, our colour had to change.

Nina has produced a map that shows how human skin colour adapted.

You see very darkly pigmented people that are concentrated in the areas of high UV

and then much more lightly

or depigmented people as you get closer to the poles under conditions of very low of very low UV.

So each population works out a balancing act, so they're protected enough that their DNA is OK, but they still have enough UV to make vitamin D?

Precisely.

This interaction between our skin and the sun is so finely balanced

that even in a single individual it can adapt and change.

To show us, Nina is looking for the people with the biggest difference in colour between parts of the body

that get a lot of sun exposure and parts that get very little. So let's look here.

Now we don't see a lot of difference here between your upper inner arm and your forehead.

They're pretty closely similar.

And with the two very lightly pigmented people, there's very, very little difference.

And similarly, at the very other end of the line, with our most darkly pigmented person, there's very little difference.

But in the middle of the line, things are different.

So if we look at some of these individuals, the difference is really quite great.

The unexposed skin versus the exposed skin, we can really see a visible difference.

And all of these people have sort of moderately to darkly pigmented skin and they have tremendous abilities to tan.

Tanning is the solution to living at latitudes where sunlight changes dramatically throughout the year.

In these regions, people produce melanin to protect them in summer and then lose it in winter.

All of this suggests a problem because today we jet all over the world, we live in countries which we weren't born in.

Does that cause problems?

Now we have to modify our lifestyle.

We have to think about whether we protect our skin from ultraviolet radiation, or whether we take vitamin D supplements.

It's only recently we've been able to take measures like this to help control our relationship with the sun.

For most of our history, this vital role was played by our own skin.

Thank you.

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אותו ערוץ

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המלץ על סרטון

167 משפטים

Vocabulary and speaking notes for this lesson

This video has 34 sentences and 479 words to shadow. The speech runs for 3:56. The speaker talks at a steady 122 words per minute, a comfortable pace for shadowing. 83% of the words are among the 3,000 most common in English; the rest is worth studying before you start.

Key vocabulary in this video

15 words from the video worth learning, with pronunciation and meaning:

Word	Pronunciation	Meaning
vitamin noun	/ˈvɪt.ə.mɪn/	Any of a specific group of organic compounds essential in small quantities for healthy human growth, metabolism, development, and body function. They are found…
exposure noun	/ɪkˈspəʊ.ʒə(ɹ)/	The condition of being exposed, uncovered, or unprotected.
adapt verb	/əˈdæpt/	To make suitable; to make to correspond; to fit or suit.
lightly adverb	/ˈlaɪtli/	In a light manner.
dramatically adverb		In a dramatic manner.
bone noun	/boʊn/	A composite material consisting largely of calcium phosphate and collagen and making up the skeleton of most vertebrates.
visible adjective	/ˈvɪzɪb(ə)l/	Able to be seen.
vital adjective	/ˈvaɪtəl/	Relating to or characteristic of life.
versus	/ˈvɝsəs/	Against; in opposition to.
similarly adverb	/ˈsɪm.ə.lə.li/	In a like style or manner.
interaction noun	/ˌɪn.təˈɹæk.ʃən/	The situation or occurrence in which two or more things act upon one another to produce an effect; the effect resulting from such a situation or occurrence.
lifestyle noun	/ˈlaɪfˌstaɪl/	A style of living that reflects the attitudes and values of a person or group.
globe noun	/ɡloʊb/	The eyeball.
radiation noun	/ˌɹeɪ.diˈeɪ.ʃən/	The shooting forth of anything from a point or surface, like diverging rays of light.
vary verb	/ˈvɛəɹi/	To change with time or a similar parameter.

Phrasal verbs you will hear

Word	Pronunciation	Meaning
work out verb	/ˌwɝk ˈaʊt/	To calculate.

Pronunciation to watch

The speaker uses 6 contractions and reduced forms, such as they're, couldn't, don't. Say them the short way, as you hear them.

The “sh” and “zh” sounds: exposure /ɪkˈspəʊ.ʒə(ɹ)/, interaction /ˌɪn.təˈɹæk.ʃən/, radiation /ˌɹeɪ.diˈeɪ.ʃən/
Long words — get the stress right: similarly /ˈsɪm.ə.lə.li/, interaction /ˌɪn.təˈɹæk.ʃən/, radiation /ˌɹeɪ.diˈeɪ.ʃən/, ultraviolet /ˌʌltɹəˈvaɪələt/

How to practise with this video

Listen to the whole video once without speaking and note the words you do not know.
Shadow it sentence by sentence at normal speed, repeating each one until your rhythm matches the speaker.
Record yourself and compare with the original, paying attention to words like vitamin, exposure, adapt.

דקדוק בסרטון הזה

המבנים שהדובר משתמש בהם הכי הרבה, עם המילים המדויקות מהסרטון:

מבנה	בסרטון
סביל (Passive voice) be + past participle — הדגש הוא על מה שקורה, לא על מי שעושה את הפעולה	are concentrated · weren't born · was played
הווה מושלם (Present perfect) have/has + past participle — פעולה שקרתה בעבר ועדיין יש לה חשיבות או השפעה עכשיו	has produced · we've been

מהי טכניקת השאדואינג?

שאדואינג היא טכניקת למידת שפה מבוססת מדע שפותחה במקור להכשרת מתורגמנים מקצועיים ופופולרית על ידי הפוליגלוט ד"ר אלכסנדר ארגואלס. השיטה פשוטה אך עוצמתית: אתה מקשיב לאודיו באנגלית ילידית וחוזר עליו בקול רם מיד — כמו צל העוקב אחרי הדובר עם עיכוב של 1–2 שניות בלבד. בניגוד להאזנה פסיבית או תרגילי דקדוק, שאדואינג מכריח את המוח והשרירים בפה לעבד ולשחזר דפוסי דיבור אמיתיים בו זמנית. מחקרים מראים שזה משפר משמעותית את דיוק ההגייה, האינטונציה, הקצב, הדיבור המחובר, הבנת השמיעה ושטף הדיבור — מה שהופך אותו לאחת השיטות היעילות ביותר להכנה לIELTS Speaking ולתקשורת באנגלית בעולם האמיתי.

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Shadowing Practice: The Evolution of Human Skin Colour | BBC Earth Science - Learn English Speaking with Video

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