Published online 17 February 2009 | Nature | doi:10.1038/457945a
Rethinking
silk's origins
Did the Indian subcontinent
start spinning without Chinese know-how?
Philip
Ball
Ancient
silk strands have been found in artefacts from Pakistans
Indus valley.I. Good
New findings suggest that silk making was not an exclusively
Chinese technological innovation, but instead arose independently
on the Indian subcontinent.
Ornaments
from the Indus valley in east Pakistan, where the Harappan
culture flourished more than 4,000 years ago, seem to contain
silk spun by silk moths native to the region. What's more,
the silk seems to have been processed in a way previously
thought to have been a closely guarded secret within China.
There
is hard and fast evidence for silk production in China back
to around 2570 BC; the newly discovered objects are believed
to date from between 2450 BC and 2000 BC, making them similarly
ancient. There have been no previous finds of manufactured
silk at sites outside China before about 1500 BC.
"This
is the first evidence for silk anywhere out of China at
such an early date," says Irene Good of Harvard University
in Cambridge, Massachusetts, one of the authors of the study.
"It was a complete surprise."
The
objects come from two sites in the Indus valley: the city
of Harappa itself, the hub of the Indus civilization, and
Chanhu-daro in Sindh province, about 500 kilometres to the
south. They were collected from archaeological excavations
in 1999 and 2000 conducted by the Harappa Archaeological
Research Project (HARP), a USPakistan collaboration.
Because of the sheer volume of artefacts amassed so far,
they have only recently been studied in detail.
Good,
working with HARP directors Richard Meadow of Harvard University
and Jonathan Kenoyer of the University of Wisconsin in Madison,
used an electron microscope to look at the fine structure
of silk strands found in necklaces and bangles.
The
precise shape of the individual silk threads determined
by the shape of the orifice through which they are extruded
is characteristic of the species of silk moth that
produced the strands.
In
a paper in the journal Archaeometry, the researchers show
that the Harappa samples two metal ornaments
contain silk from species of Antheraea moths indigenous
to south Asia (I.
L. Good, J. M. Kenoyer and R. H. Meadow Archaeometry doi:10.1111/j.1475-4754.2008.00454.x;
2009). The origin of the Chanhu-daro silk, threaded
through soapstone beads, is less clear, but it may be from
one of the same species. Chinese silk comes from the domesticated
silk moth Bombyx mori.
The
Harappan silks seem to have been made by a process called
reeling, in which the strands are collected on a bobbin
rather than being twisted in short segments into a thread.
The researchers say that reeling was thought to have been
part of a silk technology known only to China until the
early centuries AD. Now it seems that knowledge was not
so exclusive.
"Archaeology
in early China is showing increasingly there were connections
outside China," says Shelagh Vainker, a silk expert
at the Ashmolean Museum in Oxford, UK. "It doesn't
seem unreasonable." But she sees evidence for silk
production in China "significantly earlier" than
25002000 BC, which would suggest China could still
claim priority.
"I
believe that the people of the Indus civilization either
harvested silkworm cocoons or traded with people who did,
and that they knew a considerable amount about silk,"
says Good. She does, however, acknowledge that some might
find this challenging: "National pride is at stake
with such a discovery as this."