Why does our metabolism slow down as we age?
PATRICK HORNSEY, CHESTER HILL, NSWTIM CROWE,
ASSOCIATE PROFESSOR IN EXERCISE AND NUTRITION SCIENCES,
DEAKIN UNIVERSITY, SAYS:
Beginning about age 25, the body starts to slowly lose muscle. The more muscle
a person has, the more energy (kilojoules) they will burn 24 hours a day, even
without exercise. That’s because muscle is a high-maintenance tissue and requires
more kilojoules than fat to sustain itself. Less muscle means a lower metabolic
rate. Some of our organs also decrease in size with age, such as the brain, kidneys,
liver and spleen, and this means they use less energy to function.TWITCHING AND TWEETING
We asked you for your favourite
birdwatching sites in Australia and
here’s what you had to say on our
website, Facebook and Twitter.The Arnhemland Barramundi
Nature Lodge, NT: more than 200
species within a 50km radius of the
lodge; Gouldian fi nches in fl ocks,
northern rosellas and hooded
parrots, chestnut rail and more.
RICHARD EUSSENPutta Bucca Wetlands in Mudgee,
NSW, is a fabulous place, especially
considering it’s within easy walking
distance of town. Also Rylstone Dam
near, of course, Rylstone, which as well
as being a fabulous birding spot, is an
excellent chance to maybe see a
platypus in the wild.
STEVE MENCINSKYMy front verandah: have layered
plantings of eucalypts, callistemon,
hakea and correa. The Tassie blue
gum acts as drop-in centre for all
the locals and travelling birdies.
SUZANNE DWYERGlen Davis in the Capertee Valley, NSW:
free camping (including hot showers,
power, and playground and BBQ area)
in the community park, where you’re
surrounded by Wollemi National Park
and more than 235 bird species. Oh
my, what an orchestra to wake up to in
the morning!
KERI HENNESSYEdwards Point Wildlife Reserve
near St Leonards in Victoria.
HELEN WRIGHTGET INVOLVED IN
THE CONVERSATION
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How did the mistletoe plant evolve – was it fi rst a tree in its own
right or was it always a parasite?
BOB CURRIE, BRISBANE, QLDDAVID M. WATSON,
ASSOCIATE PROFESSOR IN ECOLOGY, CHARLES STURT UNIVERSITY, SAYS:
Mistletoes are stem-parasitic plants from fi ve different families, but all evolved from root-
parasitic ancestors in the sandalwood group of fl owering plants. We can infer that the fi rst
root parasites in this group (related to olive trees) acquired the ability to take nutrients and
water from the roots of other plants, possibly evolving in low-productivity soils where access
to nutrients is limited. At a later date – and occurring independently in all fi ve families of
mistletoe – these plants shifted from parasitising roots below ground to parasitising stems
above ground. And it’s clearly a winning strategy: at more than 1500 species, mistletoes are
one of the most successful groups of parasitic plants worldwide.
A
ASK AN EXPERT
ANDREW GREGORYGOT A
QUESTION FOR
AN EXPERT?
Email it to
editorial@ausgeo.
com.auYOUR AG
Your AG is edited by Lauren SmithThe so-called variable mistletoe
(Amyema congener), seen here
in the Daintree Rainforest,
QLD, is a common species
from eastern Australia.126 A G
ag0914p126_yourag - 126 2014-08-12T12:11:49+10:00